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Signal box prefix codesLast update 15 March 2019
Additional information is always gratefully received, whether entirely new records (particularly historical records), or information to fill in gaps or correct errors, via the contact link under the Miscellaneous entry in the navigation bar above. Thank you.
Please select a starting letter from the links below:
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Croydon Tramlink signal codes can be found on the Croydon Tramlink Unofficial Site.
Although the Docklands Light Railway is an automated system, trains are driven manually in the depots. At present, only five signal codes are known, all for Poplar depot. These are AS, AT, DA, DB and WA.
It appears that the only labelled signals are in the depot area or are points indicators with codes based on the nearby station. In addition, road traffic crossings are labelled sequentially from ET1. Prefixes known at present are:
| Code | Area |
|---|
| AIR | Airport |
| DEP | Depot |
| HAY | Haymarket |
| YPL | York Place |
'Stop' signals are labelled in the form DEP R1 04 (in three rows), points indicators in the form HAY PPI 02 (again in three rows).
Most signals appear not to carry a prefix. Those seen with a prefix carry A.
London Underground (and its predecessors) has a complex signal labelling system. A summary can be found below. Note that the Underground is not my particular speciality: most of the raw data coming from District Dave's site (Page 1, Page 2, Page 3 (broken links)), and from Tube Prune (these sources are not identical), in addition to other observations. In addition to these codes, a 1930s photograph shows signals at Stanmore (controlled from Wembley) displaying Y8LA and Y4LA on the same post. The Y represents Stanmore area control, and the L signifies "push-pull lever control". The smaller A denotes platform 1; platform 2 had equivalent numbers with a 'B'.
| Code | Control centre or relay room | Current Line (for numbering series purposes) | Date code used (where known) | Became or taken over by (where known) |
|---|
| BMX | "Special" signal | Bakerloo | - | |
| A | Automatic signals | [General use] | - | |
| S | Automatic signals | Northern | All gone by 2014 | - |
| X | Last automatic signal before controlled area (also used in combination with controlled area code) | [General use] | - | |
| R | Repeater signals | [used on all lines] | - | |
| FDX | Floodgate signals at Embankment and South Kensington | District | 1939- | - |
| FNX | Floodgate signals at Bank, Charing Cross, London Bridge and Waterloo | Northern | 1939-2014 | - |
| FNX | Floodgate (?) signals at Kennington, Moorgate and Tottenham Court Road | Northern | 1958-2014 | - |
| FX | Floodgate signals at Green Park and Oxford Circus | Victoria | 1968-2012 | VGPF |
| CAT | Canning Town | Jubilee | 2010- | - |
| TN | Canning Town | Jubilee | 1999-2010 | CAT |
| X | Floodgate signals | Bakerloo | 1990- | - |
| FBX | Floodgate signals at Embankment and Waterloo | Bakerloo | 1939-1990 | X |
| PNX | Possession protection signals | [used on all lines] | - | |
| WL | Acton Town | District | 1905- | - |
| E | Aldersgate (Barbican) | Metropolitan/Circle | 1865-1954 | OG |
| P | Aldersgate (Widened Lines) | Metropolitan/Circle | 19xx-1924 | E |
| H | Aldgate | Metropolitan/Circle | 1909-1946 | OB |
| OB | Aldgate and Aldgate East | Circle | 1946- | - |
| EL | Aldgate East | District | 1906-1946 | OB |
| JW | Amersham | Metropolitan | 1960- | - |
| K | Angel | Northern | 1919-1959 | - |
| ARC | Archway | Northern | 2013- | - |
| J | Arnos Grove | Piccadilly | 1932-1982 | PJ |
| PJ | Arnos Grove | Piccadilly | 1982- | - |
| BAS | Baker Street | Jubilee | ? | - |
| BM | Baker Street | Jubilee | 1939-? | BAS |
| MB | Baker Street | Metropolitan | 1947- | - |
| MBX | Baker Street intermediate stop signals (indicates an X signal) | Metropolitan | 1947- | - |
| RMB | Repeater for Baker Street signals | Metropolitan | 1947- | - |
| M | Baker Street | Metropolitan/Circle | 1928-1947 | MB |
| A | Baker Street (also recorded as B in some sources) | Metropolitan/Circle | 1913-1928 | M |
| B | See Baker Street (A) | |||
| B | Bank | Central | 1914-1941 | CB |
| BAN | Bank | Central | 1996- | - |
| CB | Bank | Central | 1941-1971 | - |
| OG | Barbican | Circle | 1954-1979 | - |
| FF | Barking And Upney | District | 1960- | - |
| FFX | Barking And Upney intermediate stop signals (indicates an X signal) | District | 1960- | - |
| RFF | Repeater for Barking And Upney signals | District | 1960- | - |
| RFFX | Repeater for Barking And Upney intermediate stop signals (?) | District | 1960- | - |
| BAR | Barkingside | Central | 1996- | - |
| LN | Barkingside Ground Frame | Central | 1948-1965 | - |
| WC | Barons Court | District | 1962-1983 | - |
| WD | Barons Court | District | 1906- | - |
| X | Barons Court surface stock detector | District | ?? | - |
| BER | Bermondsey | Jubilee | 2010- | - |
| TR | Bermondsey | Jubilee | 1999-2010 | BER |
| BEG | Bethnal Green | Central | 1995- | - |
| LC | Bethnal Green | Central | 1946-1995 | - |
| VBR | Blackhorse Road | Victoria | 2010- | - |
| LY | Blake Hall Ground Frame (no signals present) | Central | 1957-1967 | - |
| BOS | Bond Street | Jubilee | 2010- | - |
| X | Borough | Northern | 1922-1923 | - |
| WS | Boston Manor | District | 1974- | - |
| EP | Bow Road | District | 1907-1964 | - |
| AA | Brent Cross | Northern | 1926-1937 | - |
| C | British Museum | Central | 1900-1933 | CB |
| VE | Brixton | Victoria | 1971-2010 | VBN |
| VBN | Brixton | Victoria | 2010- | - |
| FB | Bromley-By-Bow | District | 1960- | - |
| FBX | Bromley-By-Bow advanced starting board | District | 1960- | - |
| FRFB | Fog repeater for Bromley-By-Bow signals (similar for other fog repeaters, not all are known and shown here) | District | 1960- | - |
| FRFBX | Fog repeater for Bromley-By-Bow intermediate stop signals | District | 1960- | - |
| RFB | Repeater for Bromley-By-Bow advanced signals | District | 1960- | - |
| RFBX | Repeater for Bromley-By-Bow advanced starting board | District | 1960- | - |
| BUH | Buckhurst Hill | Central | 1996- | - |
| LS | Buckhurst Hill Ground Frame | Central | 1948-1965 | - |
| BT | Camberwell Green (planned, not used) | Bakerloo | - | - |
| E | Camden Town | Northern | 1907-2013 | CTN |
| CTN | Camden Town | Northern | 2013- | - |
| CDW | Canada Water | Jubilee | 2010- | - |
| TK | Canada Water | Jubilee | 1999-2010 | CDW |
| E | Canal Junction | East London | 1913-1950 | ET |
| ET | Canal Junction | East London | 1950-1997 | - |
| ETX | Canal Junction advance starting signals | East London | 1950-1997 | - |
| FRETX | Canal Junction advance starting signal fog repeater | East London | 1950-1997 | - |
| RET | Canal Junction intermediate stop repeater signals | East London | 1950-1997 | - |
| RF | Canal Junction | Proposed Fleet Line/East London | - | - |
| CRW | Canary Wharf | Jubilee | 2010- | - |
| TL | Canary Wharf | Jubilee | 1999-2010 | CRW |
| MJ | Canons Park | Metropolitan | 1941-1971 | - |
| WW | Canons Park | Metropolitan | 1941-1941 | MJ |
| CAP | Canons Park | Jubilee | 2011- | - |
| JT | Chalfont | Metropolitan | 1949-1959, 1960- | JW |
| JW | Chalfont | Metropolitan | 1959-1960 | JT |
| CHL | Chancery Lane | Central | 1996- | - |
| CHX | Charing Cross | Jubilee | 2010- | - |
| TG | Charing Cross | Jubilee | 1978-2010 | CHX |
| C | Charing Cross | Northern | 1937-2013 | CHX |
| RC | Charing Cross | Proposed Fleet Line/East London | - | - |
| CHX | Charing Cross | Northern | 2013- | - |
| JV | Chesham | Metropolitan | 1949-1970 | - |
| CHI | Chigwell | Central | 1996- | - |
| JS | Chorleywood | Metropolitan | 1954-1970 | - |
| T | Clapham Common | Northern | 1919-1976 | - |
| M | Cockfosters | Piccadilly | 1933-1982 | PM |
| PM | Cockfosters | Piccadilly | 1982- | - |
| AC | Colindale | Northern | 1924-2013 | CDL |
| CDL | Colindale | Northern | 2013- | - |
| B | Covent Garden | Piccadilly | 1906-1931 | C |
| C | Covent Garden | Piccadilly | 1931-1979 | - |
| FPX | Green Park/Russell Square 'special' signals (exact meaning uncertain) | Piccadilly | 1958- | - |
| EC | Cromwell Road | District | 1906-1967 | - |
| B | Croxley | Metropolitan | 1924-1970 | - |
| FG | Dagenham East | District | 1960- | - |
| DEB | Debden | Central | 1996- | - |
| LU | Debden | Central | 1949-1996 | DEB |
| D | Deptford Road Junction (GF emergency crosover) | East London | 1913-1950 | - |
| MX | Dollis Hill | Metropolitan | 1938-1939 | - |
| DOH | Dollis Hill | Jubilee | ? | - |
| PB | Down Street | Piccadilly | 1979- | - |
| LD | Drapers Field (Leyton) (temporary reversing siding) | Central | 1946-1947 | - |
| B | Drayton Park | Northern City | 1904-1953 | NC |
| NC | Drayton Park and Finsbury Park | Northern City | 1939-1976 | - |
| EAB | Ealing Broadway | Central | 1993- | - |
| L | Ealing Broadway | Central | 1920-1952 | WP |
| WP | Ealing Broadway | District | 1905- | - |
| WM | Ealing Common | District | 1905- | - |
| WMX | Ealing Common depot | District | ?? | - |
| EC | Earls Court (Main) | District | 1966- | - |
| EA | Earls Court East | District | 1905-1936 | EC |
| WA | Earls Court West | District | 1905-1966 | EC |
| LMR | Distant signal for Earls Court junction Code not carried: used on signalling plan to denote London Midland Region (BR) signal box control |
|||
| EAA | East Acton | Central | 1996- | - |
| MS | Eastcote (also recorded as MR in some sources) | Metropolitan | 1948-1966 | - |
| MR | See Eastcote (MS) | |||
| T | Eastcote (also recorded as R in some sources) | Metropolitan | 1930-1948 | MS |
| R | See Eastcote (T) | |||
| NP | East Finchley | Northern | 1939-1961 | - |
| FRNP | Fog repeater for East Finchley signals | Northern | 1939-1961 | - |
| EFN | East Finchley | Northern | 2013- | - |
| FE | East Ham | District | 1960- | - |
| FEX | East Ham last automatic signal before controlled area | District | 1960-1995 | - |
| RFE | Repeater for East Ham signals | District | 1960- | - |
| FD | East Ham (planned, not used) | District | - | - |
| AE | Edgware | Northern | 1924-2013 | EDG |
| EDG | Edgware | Northern | 2013- | - |
| A | Edgware Road | Bakerloo | 1907-1913 | - |
| B | Edgware Road | Metropolitan/Circle | 1907-1951 | OP |
| OP | Edgware Road | Metropolitan/Circle | 1951- | - |
| ROPX | Repeater for Edgware Road intermediate stop signals | Metropolitan/Circle | 1951- | - |
| BS | Elephant And Castle | Bakerloo | 1941-1991 | - |
| E | Elephant And Castle | Bakerloo | 1906-1941 | BS |
| Q | Elephant And Castle | Northern | - | |
| EH | Embankment | District | 1905- | - |
| EPP | Epping | Central | 1996- | - |
| LW | Epping | Central | 1949-1996 | - |
| J | Euston | Northern | 1919-2013 | EUS |
| EUS | Euston | Northern | 2013- | - |
| VEU | Euston | Victoria | 2010- | - |
| OZ | Euston Square | Metropolitan/Circle | 1941-19xx | - |
| FAI | Fairlop | Central | 1996- | - |
| LM | Fairlop Ground Frame | Central | 1948-1964 | - |
| FRLM | Fairlop fog repeater | Central | 1948-1997 | - |
| A | Fairlop automatic signals | Central | 1948-1997 | - |
| FR | Fairlop automatic signals fog repeaters | Central | 1948-1997 | - |
| D | Farringdon | Metropolitan/Circle | 1909-1956 | OH |
| OH | Farringdon | Metropolitan/Circle | 1956- | - |
| M | Farringdon (Widened Lines) | Metropolitan/Circle | 19xx-1924 | D |
| RD | Fenchurch Street | Proposed Fleet Line/East London | - | - |
| NQ | Finchley Central | Northern | 1940-1969 | - |
| NQX | Finchley Central advance starting board | Northern | 1940-1969 | - |
| RNQ | Repeater for Finchley Central signals | Northern | 1940-2013 | - |
| FRNQ | Fog repeater for Finchley Central signals | Northern | 1940-1969 | - |
| FNC | Finchley Central | Northern | 2013- | - |
| FIR | Finchley Road | Jubilee | 2010- | - |
| JD | Finchley Road | Jubilee | 1984-2010 | FIR |
| MD | Finchley Road | Metropolitan | 1937- | - |
| C | Finchley Road (also recorded as D) | Metropolitan | 1911-1937 | MD |
| D | See Finchley Road (C) | |||
| C | Finsbury Park | Northern City | 1904-1939 | NC |
| F | Finsbury Park | Piccadilly | 1906-1965 | VK |
| VK | Finsbury Park | Victoria | 1968-2010 | VFP |
| VKX | Temporary Finsbury Park signals whilst rebuilding to divert Piccadilly line | Victoria | 1968 | VFP |
| VFP | Finsbury Park | Victoria | 2010- | - |
| GAH | Gants Hill | Central | 1996- | - |
| EE | Gloucester Road/South Kensington | District | 1906-1957 | EC |
| K | Gloucester Road | Metropolitan/Circle | 1909-1952 | OQ |
| OQ | Gloucester Road | Metropolitan/Circle | 1952-1957 | EC |
| G | Golders Green | Northern | 1907-2013 | GGN |
| GGN | Golders Green | Northern | 2013- | - |
| GRH | Grange Hill | Central | 1997- | - |
| LK | Grange Hill (subsiduary to Hainault) (code never allocated though provision made), also recorded as LL | Central | 1948-1997 | GRH |
| B | Great Central (Marylebone) | Bakerloo | 1907-1915 | - |
| GRP | Green Park | Jubilee | 2010- | - |
| TF | Green Park | Jubilee | 1999-2010 | GRP |
| VGP | Green Park | Victoria | 2010- | - |
| VGPF | Green Park/Oxford Circus floodgate signals | Victoria | 2012- | - |
| CL | Greenford | Central | 1947-1960 | - |
| CLX | Greenford | Central | 1947-1948 | - |
| GRE | Greenford | Central | 1996- | - |
| HAI | Hainault | Central | 1997- | - |
| LL | Hainault/Grange Hill | Central | 1948-1997 | - |
| LLX | Hainault/Grange Hill advance starting signals (?) | Central | 1948-1997 | - |
| FRLX | Hainault/Grange Hill fog repeater | Central | 1948-1997 | - |
| H | Hammersmith | Hammersmith and City | 1921-1951 | OZ |
| OZ | Hammersmith | Hammersmith and City | 1951- | - |
| A | Hammersmith | Piccadilly | 19xx-1932 | WD |
| F | Hampstead | Northern | 1907-2013 | HMP |
| HMP | Hampstead | Northern | 2013- | - |
| HAL | Hangar Lane | Central | 1996- | - |
| WO | Hanger Lane Junction (also recorded as WN) | District | 1905-1925 | WM |
| WN | See Hanger Lane Junction (WO) | |||
| N | Harrow North | Metropolitan | 1908-1948 | JB |
| H | Harrow South | Metropolitan | 1908-1948 | JB |
| J | Harrow Station | Metropolitan | 1908-1948 | JB |
| JB | Harrow-on-the-Hill | Metropolitan | 1948- | - |
| WW | Hatton Cross | Piccadilly | 1975- | - |
| WY | Heathrow Central | Piccadilly | 1977- | - |
| AB | Hendon Central | Northern | 1923-1930 | - |
| NU | High Barnet | Northern | 1940-2013 | HBT |
| HBT | High Barnet | Northern | 2013- | - |
| VJ | Highbury | Victoria | 1968-2010 | VHY |
| VHY | Highbury & Islington | Victoria | 2010- | - |
| H | Highgate (Archway) | Northern | 1907-1939 | NN |
| NN | Highgate (Archway) | Northern | 1939-2013 | ARC |
| NH | Highgate Depot Panel | Northern | 1989- | - |
| EB | High Street Kensington | District | 1907-1936 | - |
| ED | High Street Kensington | District | 1967- | - |
| J | High Street Kensington | Metropolitan | 1909-1926 | EB |
| MV | Hillingdon | Metropolitan | 1948-1966 | - |
| V | Hillingdon | Metropolitan | 1930-1948 | MV |
| C | Holborn | Central | 1933-1941 | CC |
| CC | Holborn | Central | 1941-1994 | HOL |
| HOL | Holborn | Central | 1994- | - |
| D | Holborn/Aldwych | Piccadilly | 1906-1980 | PD |
| PD | Holborn/Aldwych | Piccadilly | 1980- | - |
| HOP | Holland Park | Central | 1996- | - |
| FJ | Hornchurch | District | 1959- | - |
| FK | Hornchurch (code was never used) | District | - | FJ |
| WT | Hounslow Central | District | 1910- | - |
| X | Hounslow Central surface stock detector | District | ?? | - |
| WS | Hounslow East/Town | District | 1905-1923 | - |
| WX | Hounslow West | District | 1926-1975 | - |
| WT | Hounslow West/Barracks | District | 19xx-c1905 | - |
| A | Hyde Park Corner | Piccadilly | 1906-1931 | B |
| B | Hyde Park Corner | Piccadilly | 1931-1979 | PB |
| WH | Junction with LWSR at Ravencscourt Park (suspected but not confirmed) | District | - | |
| A | Kennington | Northern | 1926-1937 | B |
| B | Kennington | Northern | 1937-2013 | KEN |
| Y | Kennington (temporary control) | Northern | 1923-19xx | - |
| KEN | Kennington | Northern | 2013- | - |
| D | Kennington Road (Lambeth North) | Bakerloo | 1906-1939 | BR |
| KIL | Kilburn | Jubilee | 2010- | - |
| KIN | Kingsbury | Jubilee | 2011- | - |
| OJ | Kings Cross | Metropolitan | 1941- | - |
| OJX | ||||
| C | Kings Cross | Metropolitan/Circle | 1908-1958 | OJ |
| J | Kings Cross | Metropolitan/Circle | 1912-1939 | - |
| L | Kings Cross | Northern | 1927-1956 | - |
| VH | Kings Cross | Victoria | 1968-2010 | VKC |
| VKC | Kings Cross St Pancras | Victoria | 2010- | - |
| E | Ladbroke Grove | Hammersmith and City | 1921-1950 | OU |
| OU | Ladbroke Grove | Hammersmith and City | 1950-1983 | - |
| BR | Lambeth North | Bakerloo | 1939-1991 | - |
| LAG | Lancaster Gate | Central | 1996- | - |
| F | Latimer Road | Hammersmith and City | 1921-1950 | OV |
| OV | Latimer Road | Hammersmith and City | 1950-1957 | - |
| RK | Lewisham | Proposed Fleet Line/East London | 1973 | - |
| LE | Leyton | Central | 1947-1971 | - |
| LEY | Leyton | Central | 1996- | - |
| LES | Leytonstone | Central | 1997- | - |
| LF | Leytonstone | Central | 1947-1997 | - |
| LFX | Leytonstone | Central | 1947-1997 | - |
| A | Liverpool Street | Central | 1912-1937 | LB |
| LB | Liverpool Street | Central | 1937-1997 | LIS |
| FCX | Tottenham Court Road/Liverpool Street 'special' signals (exact meaning uncertain) | Central | 1958-1999 | - |
| LIS | Liverpool Street | Central | 1997- | - |
| G | Liverpool Street | Circle | 1910-1954 | OD |
| OD | Liverpool Street | Circle | 1954- | - |
| LOB | London Bridge | Jubilee | 2010- | - |
| TJ | London Bridge | Jubilee | 1999-2010 | LOB |
| P | London Bridge | Northern | 1919-2014 | - |
| D | London Road Depot | Bakerloo | 1906-1915 | D |
| B | Lords | Metropolitan | 1910-1937 | MC |
| MC | Lords | Metropolitan | 1937-1971 | ML |
| LOU | Loughton | Central | 1997- | - |
| LT | Loughton | Central | 1948-1997 | - |
| EG | Mansion House | District | 1973- | - |
| EI | Mansion House | District | 1928-1973 | EG |
| CD | Marble Arch | Central | 1941-1994 | MAA |
| D | Marble Arch | Central | 1914-1941 | CD |
| MAA | Marble Arch | Central | 1994- | - |
| MIE | Mile End | Central | 1996- | - |
| NV | Mill Hill East Ground Frame | Northern | 1943-1964 | - |
| EK | Minories Junction | District | 1906-1909 | EL |
| D | Moor Park | Metropolitan | 1924-1953 | - |
| JG | Pinner | Metropolitan | 1962-1971 | - |
| OE | Moorgate | Circle | 1956- | - |
| F | Moorgate | Metropolitan/Circle | 1909-1956 | OE |
| M | Moorgate | Northern | 1919-2013 | MGT |
| MGT | Moorgate | Northern | 2013- | - |
| A | Moorgate | Northern City | 1904-1922 | D |
| D | Moorgate | Northern City | 1922-1937 | ND |
| ND | Moorgate | Northern City | 1937-1976 | - |
| R | Moorgate (Widened Lines) | Metropolitan/Circle | 19xx-1926 | F |
| Y | Morden | Northern | 1926-2013 | MOR |
| MOR | Morden | Northern | 2013- | - |
| Z | Morden Depot Ground Frame (unofficial code) | Northern | 1926- | - |
| D | Mornington Crescent | Northern | 1907-1924 | E |
| JM | Neasden | Jubilee | 1985-2011 | NEA |
| NEA | Neasden | Jubilee | 2011- | - |
| F | Neasden | Metropolitan | 1911-1938 | MF |
| MM | Neasden | Metropolitan | 1985- | - |
| JF | Neasden (code never used) | Jubilee | 1985- | - |
| MH | Neasden North | Metropolitan | 1939-1987 | - |
| MF | Neasden South | Metropolitan | 1938-1987 | MM |
| RJ | New Cross | Proposed Fleet Line/East London | - | - |
| RH | New Cross Gate | Proposed Fleet Line/East London | - | - |
| LP | Newbury Park | Central | 1947-1994 | NEP |
| NEP | Newbury Park | Central | 1994- | - |
| CJ | North Acton | Central | 1947-1996 | NOA |
| K | North Acton | Central | 1920-1947 | CJ |
| NOA | North Acton | Central | 1996- | - |
| WU | North Ealing | District | 1907-1971 | - |
| NOG | North Greenwich | Jubilee | 2010- | - |
| TM | North Greenwich | Jubilee | 1999-2010 | NOG |
| LX | North Weald | Central | 1957-1978 | - |
| WR | Northfields | District | 1916- | - |
| CP | Northolt | Central | 1960-1996 | - |
| NOR | Northolt | Central | 1996- | - |
| VN | Northumberland Park | Victoria | 1968-2010 | - |
| VNP | Northumberland Park | Victoria | 2010- | - |
| E | Northwood | Metropolitan | 1924-1962 | JF |
| JF | Northwood | Metropolitan | 1962-1962 | - |
| F | Northwood Hills Siding Ground Frame | Metropolitan | 1924-1953 | - |
| JE | Northwood Hills Temporary Box | Metropolitan | 1961-1962 | - |
| NHG | Notting Hill Gate | Central | 1996- | - |
| K | Oakwood | Piccadilly | 1933-1982 | PK |
| PK | Oakwood | Piccadilly | 1982- | - |
| L | Old Street | Northern City | 1919-1922 | - |
| LZ | Ongar | Central | 1957-1969 | LX |
| WR | Osterley Park | District | 19xx-1910 | - |
| OXC | Oxford Circus | Central | 1996- | - |
| VOC | Oxford Circus | Victoria | 2010- | - |
| BD | Paddington | Bakerloo | 1939- | - |
| C | Paddington | Bakerloo | 1913-1939 | BD |
| OR | Paddington Suburban (some doubt whether code used) | Circle | - | |
| NH | Park Junction | Northern | 1939-1984 | - |
| WF | Parsons Green | District | 1905- | - |
| PER | Perivale | Central | 1996- | - |
| B | Piccadilly Circus | Bakerloo | 1915-1939 | BP |
| BP | Piccadilly Circus | Bakerloo | 1939- | - |
| BPZ | Piccadilly Circus station starting signals (controlled from Bakerloo cabin) | Piccadilly | 1939-1980 | - |
| BZ | Piccadilly Circus station starting signals (controlled from Bakerloo cabin) | Piccadilly | 1934-1939 | BPZ |
| Y | Piccadilly Circus station starting signals (controlled from Bakerloo cabin) | Piccadilly | 1915-1927 | - |
| VPM | Pimlico | Victoria | 2010- | - |
| G | Pinner | Metropolitan | 1924-1962 | JD |
| JD | Pinner | Metropolitan | 1962-1970 | - |
| FC | Plaistow | District | 1959-7 May 1960 (?) | - |
| FCX | Plaistow last automatic signal before controlled area | District | 1959- | - |
| RFC | Repeater for Plaistow signals | District | 1959- | - |
| A | Praed Street Junction | Metropolitan/Circle | 1908-1926 | B |
| MZ | Preston Road | Metropolitan | 1938-1948 | - |
| WG | Putney Bridge | District | 1905- | - |
| QUE | Queensbury | Jubilee | 2011- | - |
| A | Queens Park | Bakerloo | 1915-1937 | BB |
| BB | Queens Park | Bakerloo | 1937- | - |
| CE | Queens Road (Queensway) | Central | 1941-1984 | - |
| E | Queens Road (Queensway) | Central | 1914-1941 | CE |
| QUE | Queensway | Central | 1996- | - |
| MP | Rayners Lane | Metropolitan | 1985- | - |
| P | Rayners Lane | Metropolitan | 1925-1985 | MP |
| REB | Redbridge | Central | 1996- | - |
| JP | Rickmansworth | Metropolitan | 1953- | - |
| K | Rickmansworth | Metropolitan | 1910 or 1924-1953 | JP |
| ROV | Roding Valley | Central | 1996- | - |
| RE | Rotherhithe/Surrey Docks | Proposed Fleet Line/East London | - | - |
| TRX | Track replacement signal for Royal Oak (westbound) | Hammersmith and City | - | |
| X | Royal Oak (special signals activated by derailment detector in main line goods yard) | Hammersmith and City | 1970-1978 | - |
| MT | Ruislip | Metropolitan | 1948-1975 | - |
| U | Ruislip | Metropolitan | 1930-1948 | MT |
| RUG | Ruislip Gardens | Central | 1993- | - |
| MU | Ruislip Siding | Metropolitan | 1975- | - |
| EG | St James's Park | District | 1905-1967 | - |
| SJW | St Johns Wood | Jubilee | 2010- | - |
| EM | St Marys Junction (planned, not used) | District | - | - |
| STP | St Paul's | Central | 1996- | - |
| VL | Seven Sisters | Victoria | 1968-2010 | - |
| VSS | Seven Sisters | Victoria | 2010- | - |
| F | Shepherd's Bush | Central | 1914-1938 | - |
| SHB | Shepherd's Bush | Central | 1996- | - |
| A | Shoreditch | East London | 1913-1928 | - |
| B | Shoreditch/Whitechapel | East London | 1943-1995, 1998- | - |
| N | Smithfield (Widened Lines) | Metropolitan/Circle | 1909-1918 | PK |
| SNA | Snaresbrook | Central | 1996- | - |
| LG | Snaresbrook Ground Frame | Central | 1947-c1954 | - |
| WQ | South Acton | District | 1905-1932 | - |
| WV | South Harrow | District | 1932- | - |
| EF | South Kensington | District | 1967- | - |
| L | South Kensington | Metropolitan | 1909-1949 | OR |
| OR | South Kensington | Metropolitan | 1949-1957 | EC |
| SOR | South Ruislip | Central | 1996- | - |
| LH | South Woodford | Central | 1947-1972 | - |
| SOW | South Woodford | Central | 1996- | - |
| SOU | Southwark | Jubilee | 2010- | - |
| TP | Southwark | Jubilee | 1999-2010 | SOU |
| JL | Stanmore | Jubilee | 1984-2011 | STA |
| MK | Stanmore | Bakerloo | 1938-1984 | JL |
| Y | Stanmore (controlled from Wembley Park CTC) | Metropolitan | 1932-1938 | - |
| STA | Stanmore | Jubilee | 2011- | - |
| U | Stockwell | Northern | 1919-1962, 1976-2013 | SKW |
| SKW | Stockwell | Northern | 2013- | - |
| VST | Stockwell | Victoria | 2010- | - |
| B | Strand | Northern | 1907-1937 | C |
| C | Strand/Charing Cross | Northern | 1937- | - |
| STM | Stratford Market depot entrance/exit | Jubilee | 2010- | - |
| STR | Stratford | Jubilee | 2010- | - |
| TW | Stratford | Jubilee | 1999-2010 | STM/STR |
| LD | Drapers Field (near Leyton) | Central | - | |
| TY | Stratford Market Depot | Jubilee | 1999- | - |
| WW | Sudbury Hill | District | 1933-1966 | - |
| C | Surrey Docks | East London | 1913-1950 | ER |
| FECX | 'Special' signals (exact meaning uncertain) | East London | -1995 | - |
| ER | Surrey Docks/Quays | District | 1950- | - |
| ML | Swiss Cottage | Metropolitan | 1964- | - |
| SWC | Swiss Cottage | Jubilee | 2010 | - |
| THB | Theydon Bois | Central | 1996- | - |
| LV | Theydon Bois Ground Frame | Central | 1949-1967 | - |
| W | Tooting Broadway | Northern | 1926-2013 | TBY |
| TBY | Tooting Broadway | Northern | 2013- | - |
| TCR | Tottenham Court Road | Central | 1996- | - |
| VTH | Tottenham Hale | Victoria | 2010- | - |
| NT | Totteridge Ground Frame | Northern | 1940-2013 | - |
| EJ | Tower Hill | District | 1967- | - |
| WK | Turnham Green | District | 1911- | - |
| FM | Upminster | District | 1958- | - |
| MW | Uxbridge | Metropolitan | 1938- | - |
| W | Uxbridge | Metropolitan | 1930-1938 | MW |
| VVH | Vauxhall | Victoria | 2010- | - |
| VF | Victoria | Victoria | 1969-2010 | VVC |
| VVC | Victoria | Victoria | 2010- | - |
| VP | Walthamstow Central | Victoria | 1968-2010 | VWC |
| VWC | Walthamstow Central | Victoria | 2010- | - |
| WAN | Wanstead | Central | 1996- | - |
| VG | Warren Street | Victoria | 1968-2010 | VWS |
| VWS | Warren Street | Victoria | 2010- | - |
| BR | Lambeth North | Bakerloo | 1991- | - |
| BS | Elephant & Castle | Bakerloo | 1991- | |
| TH | Waterloo | Jubilee | 1999-2010 | WAT |
| WAT | Waterloo | Jubilee | 2010- | - |
| A | Watford | Metropolitan | 1924-1948 | JL |
| JL | Watford | Metropolitan | 1948-1958 | JP |
| C | Watford Junction (Croxleyhall) | Metropolitan | 1924-1955 | JP |
| JJ | Watford South Junction (Croxleyhall) | Metropolitan | 1962- | - |
| JG | Wembley Park | Jubilee | 1984-2011 | WEP |
| G | Wembley Park | Metropolitan | 1911-1937 | MG |
| MG | Wembley Park | Metropolitan | 1937- | - |
| WEP | Wembley Park | Jubilee | 2011 | - |
| WEA | West Acton | Central | 1996- | - |
| D | Westbourne Park | Hammersmith and City | 1921-1950 | OS |
| OS | Westbourne Park | Hammersmith and City | 1950-1971 | - |
| ROS | Repeater signal for Westbourne Park | Hammersmith and City | 1950-1971 | - |
| TRX | Track replacement signal for Westbourne Park (eastbound) | Hammersmith and City | - | |
| WE | West Brompton | District | 1906-1971 | - |
| TU | West Ham/Stratford (West end) | Jubilee | 1999-2010 | WEH |
| WEH | West Ham | Jubilee | 1996-2010 | - |
| D | West Hampstead | Metropolitan | 1911-1937 | MD |
| JD | West Hampstead | Jubilee | 1984-2010 | WHD |
| WHD | West Hampstead | Jubilee | 2010- | - |
| WB | West Kensington East and Olympia | District | 1906- | - |
| FRWB | Fog repeater for West Kensington East and Olympia | District | 1906- | - |
| WC | West Kensington West | District | 1906- | - |
| WES | Westminster | Jubilee | 2010- | - |
| WER | West Ruislip | Central | 1991- | - |
| CS | West Ruislip/Ruislip Gardens | Central | 1948-1991 | WER |
| CGX | White City Temporary system until main signal cabin opened |
Central | 1947-1948 | CG |
| CG | White City | Central | 1948-2000 | WHC |
| WHC | White City | Central | 1996- | - |
| EN | Whitechapel | District | 1907- | - |
| B | Whitechapel | East London | 1913- | EN |
| Q | Whitecross Street (Widened Lines) | Metropolitan/Circle | 19xx-1916 | P |
| E | Willesden Green | Metropolitan | 1911-1938 | ME |
| JE | Willesden Green | Jubilee | 1984-2010 | - |
| ME | Willesden Green | Metropolitan | 1937-1985 | JE (in part) |
| WIG | Willesden Green | Jubilee | 2010- | - |
| WOO | Woodford | Central | 1997- | - |
| LJ | Woodford | Central | 1947-2000 | WOO |
| G | Wood Green | Piccadilly | 1932-1980 | PG |
| PG | Wood Green | Piccadilly | 1980- | - |
| G | Wood Lane | Central | 1914-1948 | CG |
| J | Wood Lane Junction | Central | 1920-1938 | - |
| NS | Woodside Park Ground Frame | Northern | 1940-1965 | - |
| E | York Road | Piccadilly | 1906-1964 | - |
Originally, on the bulk of the network stop signals did not carry a prefix. Repeater signals carried R. Between Altrincham and Timperley was controlled by the national network signal box at Deansgate Junction with DJ signals in the 500 series. For the remainder of the system, a Network Rail signalling plan uses QR (Queens Road).
The system has received a new control system which has introduced new signal codes. These have a prefix based on the nearby station, and suffix S (stop signals) or P (points indicators). Prefixes known at present are:
| Code | Area |
|---|
| AIR | Manchester Airport |
| CNK | Cornbrook |
| DCF | Deansgate-Castlefield |
| EDD | East Didsbury |
| EXS | Exchange Square |
| FIR | Firsbrook |
| IRK | Irk Valley Junction |
| MKT | Market Street |
| NEB | Newbold |
| NHM | Newton Heath & Moston |
| NIS | New Islington |
| PIC | Piccadilly |
| QNS | Queens Road depot |
| ROC | Rochdale |
| SHC | Shaw & Compton |
| SPS | St Peters Square |
| SWB | St Werberghs Road |
| TFB | Trafford Bar |
| VEL | Velopark |
| VIC | Victoria [street area] |
| VIM | Victoria [Metrolink, as opposed to adjacent Network Rail signalling] |
Prefixes known are PS (points indicator), S (stop signal), LOS (limit of shunt sign, used without additional number) and SS (stop signal (?), seen near Snow Hill). Level crossing and on-street stop signals do not carry any form of label.
Prefixes for these are based on the electrification code, in addition to a P (points indicator) or S (stop signal). Other codes may also exist. Thus a stop signal at Phoenix Park carries the prefix PPS.
It appears that signals are not numbered, being on the whole just tram signals attached to road traffic lights.
No evidence of any signal prefix has been found, except on the Pelaw-South Hylton section. This is controlled from Network Rail's Tyneside signalling centre with code T.
Signal boxes without known prefixes are excluded.
| Code | Signal Box | Location | Note |
|---|
| A | Abergynolwyn | Talyllyn Railway | |
| WN | Acton Miniature Railway | Code taken as a convenient gap in District and Piccadilly codes in Acton area, and coincidentally also suggests "Westinghouse style N miniature power lever frame", the equipment fitted | |
| RWN | Repeater signals | ||
| A | At least one signal | ||
| A | Alston | South Tynedale Railway | |
| AT | Alton | Mid Hants Railway | |
| AJ | Amwell Junction | East Herts Miniature Railway | Main signals |
| S | Siding signals | ||
| AR | Angel Road | Malden and District Society of Model Engineers | |
| SN | Avondale Railway | Signals | |
| EP | Electric point machines | ||
| NR | Network Rail Training Centre, Basingstoke | Training signal | |
| BE | Baytree | Spinney Light Railway | |
| AL | Beer Heights Light Railway | Remaining (at 2014) signals near Much Natter from old signalling scheme (also has signal labelled D with no number) | |
| C | |||
| BL | Bishops Lydeard | West Somerset Railway | |
| BJ | Bridgen Training Academy | Training signal | |
| B | Britannia Crossing | Paignton & Dartmouth Railway | |
| BC | Code reported but not carried | ||
| BH | Burhill | Surrey Light Railway | |
| BJ | Boundary Junction signals | Chadwell Heath Miniature Railway | |
| DC | |||
| FE | Farr End signals | ||
| JS | |||
| PP | |||
| CL | Church Lane | Peak Railway | Code seen on drawing, not known if carried |
| CH | Cockrow Hill | Great Cockrow Railway | |
| CL | Common Lane | Gartell Light Railway | |
| CW | Cranmore West | East Somerset Railway | |
| CE | Crewe Heritage Centre miniature railway | Shorter ride past Exeter West signal box | |
| FE | "Forge" signals | Longer ride with reversal near entrance | |
| OW | "Old Works" signals | ||
| GL | Cutteslow Park | Cutteslow Park Railway, Oxford | Ground level line |
| RL | Raised level line | ||
| DD | Darley Dale | Peak Railway | Code seen on drawing, not known if carried |
| DE | Deeside | Llangollen Railway | |
| KJ | Derby | Catalis Training | Training signal |
| DD | Dingly Dell | Spinney Light Railway | |
| EG | East Grinstead | Bluebell Railway | |
| R | East Lancashire Railway | Repeater signals | |
| EL | Eastleigh Lakeside | Eastleigh Lakeside Railway | |
| EH | Elmdon Halt | Wythall Miniature Railway | |
| ES | Everglades | Great Cockrow Railway | |
| D | Down direction automatic signals | ||
| DB | Down branch automatic signals | ||
| DM | Down main automatic signals | ||
| U | Up direction automatic signals | ||
| UB | Up branch automatic signals | ||
| S | Frimley Lodge Miniature Railway | Not all signals carry a prefix | |
| GH | Greenway Halt | Paignton & Dartmouth Railway | |
| GC | Grosmont Crossing | North Yorkshire Moors Railway | |
| HC | Hampton Court Junction | Malden and District Society of Model Engineers | |
| H | Code reported but possibly not carried | ||
| HK | Hardwick | Great Cockrow Railway | |
| HK | Horsted Keynes | Bluebell Railway | |
| H | Hythe | Romney Hythe & Dymchurch Railway | Opened 1927 |
| CN | Ipswich | Rail Tech Group Training Academy | Training signal. Code from "Claydon" |
| KR | Kidderminster | Severn Valley Railway | |
| KC | Kingscote | Bluebell Railway | |
| KR | Kingsland Road | Amey Rail training school, Bristol | Training signal |
| KE | Kingsmere East | Moors Valley Railway | |
| DA | Down direction automatic signals | ||
| UA | Up direction automatic signals | ||
| L | Lakeside | Coate Water Miniature Railway [Swindon] | |
| LM | Little Moor | Beer Heights Light Railway | |
| C | Alexandra area signals | Liverpool Overhead Railway | |
| E | |||
| F | |||
| H | Herculaneum area signals | ||
| S | Automatic signals | ||
| MJ | Mole Junction | Surrey Light Railway | |
| MB | Monks Brook | Eastleigh Lakeside Railway | |
| MA | Motala | Swanage Railway | Now removed |
| MN | Much Natter | Beer Heights Light Railway | |
| MH | Museum Halt | Woodhorn Railway | |
| Q | Needham | Stevington and Turvey Light Railway | May also have (had) code N |
| NB | New Bridge | North Yorkshire Moors Railway | |
| GF | Ground frame controlled signals | ||
| R | New Romney | Romney Hythe & Dymchurch Railway | Opened 1927 |
| N | Norden | Swanage Railway | Original code |
| NX | Future code when level crossing commissioned | ||
| NW | North Weald | Epping Ongar Railway | |
| T | North Weald | Epping Ongar Railway | Training signal beside sidings |
| OO | Old Oak | Spinney Light Railway | |
| OG | Ongar | Epping Ongar Railway | |
| VO | Orchard Green Junction | Isle of Wight Railway | Museum demonstration signal |
| AF | Original code ("April Fool"), soon replaced | ||
| PS | Paignton South | Paignton & Dartmouth Railway | |
| PW | Pinesway Junction | Gartell Light Railway | |
| S | Pinewood Railway [Wokingham] | ||
| C S |
|||
| RG | Prospect Park | Reading Society of Model Engineers | Ground level line |
| RR | Raised level line | ||
| QP | Queens Park | Paignton & Dartmouth Railway | |
| R | Robertsbridge | Kent & East Sussex Railway | Applied to at least one ground shunt signal |
| WJ | Rugby | Signalling Engineering School and Technical Assessment Centre (GM Rail Services) | Training signal: original site (33 Somers Road, Rugby) |
| GM | Training signal: new site (65 Somers Road, Rugby) | ||
| ED | Slateford | Slateford Signalling School | Training signal |
| KS | |||
| Z | South Kensington | London Underground Signalling School (in disused "deep level" tunnel) | Training signal |
| SY | Spinney | Spinney Light Railway | |
| SB | Steaming Bays | Wythall Miniature Railway | |
| SP | Sutton | Sutton Life Educational Centre | Track safety simulator signal |
| TE | Tunnel East | Beer Heights Light Railway | Also referred to as T'Other End |
| NR | Walsall | Network Rail training school | Training signal |
| EH | West Ashfield (London Underground training "station" in West Kensington) | Training signal | |
| WB | Willowbank | Malden and District Society of Model Engineers | |
| W | Code reported but possibly not carried | ||
| W | Winchcombe | Gloucestershire Warwickshire Railway | Unclear whether code actually carried |