Signal box prefix codes, specials

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.

'Stop' signals are labelled in the form DEP R1 04, points indicators in the form HAY PPI 02.

Glasgow Subway signals

London Underground signals

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 & Upney	District	1960-	-
FFX	Barking & Upney intermediate stop signals (indicates an X signal)	District	1960-	-
RFF	Repeater for Barking & Upney signals	District	1960-	-
RFFX	Repeater for Barking & 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 & Castle	Bakerloo	1941-1991	-
E	Elephant & Castle	Bakerloo	1906-1941	BS
Q	Elephant & 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 & City	1921-1951	OZ
OZ	Hammersmith	Hammersmith & 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-≈1905	-
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	Kings Cross	Metropolitan	1941-	-
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 & City	1921-1950	OU
OU	Ladbroke Grove	Hammersmith & City	1950-1983	-
BR	Lambeth North	Bakerloo	1939-1991	-
LAG	Lancaster Gate	Central	1996-	-
F	Latimer Road	Hammersmith & City	1921-1950	OV
OV	Latimer Road	Hammersmith & 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 & City		-
X	Royal Oak (special signals activated by derailment detector in main line goods yard)	Hammersmith & 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-≈1954	-
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 & City	1921-1950	OS
OS	Westbourne Park	Hammersmith & City	1950-1971	-
ROS	Repeater signal for Westbourne Park	Hammersmith & City	1950-1971	-
TRX	Track replacement signal for Westbourne Park (eastbound)	Hammersmith & 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	-

Luas signals

The only prefix noted (2019) are points indicators on Line B that, logically, carry B. It is thus possible that Line A points indicators carry A.

Manchester Metrolink signals

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
ASH	Ashton-Under-Lyne
BDW	Broadway
BRY	Bury
CNK	Cornbrook
CRP	Crumpsall
DCF	Deansgate-Castlefield
DYL	Droylsden
EDD	East Didsbury
EXS	Exchange Square
FIR	Firsbrook
HBC	Harbour City
IRK	Irk Valley Junction
IWM	Imperial War Museum
MEC	MediaCityUK
MKT	Market Street
NEB	Newbold
NHM	Newton Heath & Moston
NIS	New Islington
PIC	Piccadilly
POM	Pomona
QNS	Queens Road depot
ROC	Rochdale
RTC	Rochdale Town Centre
SHC	Shaw & Compton
SPS	St Peters Square
SWB	St Werberghs Road
TCR	Trafford Centre
TFB	Trafford Bar
VEL	Velopark
VIC	Victoria street area
VIM	Victoria Metrolink, as opposed to adjacent Network Rail signalling
WFD	Whitefield
WSD	Wharfside

Midland Metro signals

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.

Nottingham Tram signals

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.

Sheffield Supertram signals

It appears that signals are not numbered, being on the whole just tram signals attached to road traffic lights.

Tyne & Wear Metro signals

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.

Heritage, minor and miniature railways and other 'special' signals

Signal boxes without known prefixes are excluded. Items are shown alphabetically by signal box name or, where there is no known name, by the location.

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
C	Alexandra	Liverpool Overhead Railway
A	Alston	South Tynedale Railway
AT	Alton	Mid Hants Railway
AJ	Amwell Junction	East Herts Miniature Railway	Main signals
S	Amwell Junction	East Herts Miniature Railway			Siding signals
AR	Angel Road	Malden & District Society of Model Engineers
C		Ashmanaugh Railway
S		Ashmanaugh Railway
SN		Avondale Railway	Signals
EP		Avondale Railway			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		Beer Heights Light Railway		Remaining (at 2014) signals near Much Natter from old signalling scheme (also has signal labelled D with no number)
BL	Bishops Lydeard	West Somerset Railway
BJ	Boundary Junction	Chadwell Heath Miniature Railway
BJ		Bridgen Training Academy	Training signal
B	Britannia Crossing	Paignton & Dartmouth Railway
BC	Britannia Crossing	Paignton & Dartmouth Railway			Code reported but not carried
BE	Brookside	Brookside Miniature Railway
BH	Burhill	Surrey Light Railway
DC		Chadwell Heath Miniature Railway
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
GL	Cutteslow Park	Cutteslow Park Railway, Oxford	Ground level line
RL	Cutteslow Park	Cutteslow Park Railway, Oxford			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
DC	Dereham Central	Mid Norfolk Railway
DD	Dingly Dell	Spinney Light Railway
DR		Dragon Miniature Railway, Marple
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
F	Falconwood	Welling & District Model Engineering Society
FN	Fancott	Fancott Miniature Railway
FE	Farr End	Chadwell Heath Miniature Railway
FE	Forge	Crewe Heritage Centre miniature railway	Longer ride with reversal near entrance
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 & District Society of Model Engineers
H	Hampton Court Junction	Malden & District Society of Model Engineers			Code reported but possibly not carried
HK	Hardwick	Great Cockrow Railway
H	Herculaneum	Liverpool Overhead 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
KW	Kingsmere West	Moors Valley Railway
L	Lakeside	Coate Water Miniature Railway, Swindon
LR	Larkswood	Ridgeway Park Railway, Chingford
LM	Little Moor	Beer Heights Light Railway
E		Liverpool Overhead Railway
F
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 & Turvey Light Railway	May also have (had) code N
NB	New Bridge	North Yorkshire Moors Railway
GF	New Bridge	North Yorkshire Moors Railway			Ground frame controlled signals
R	New Romney	Romney Hythe & Dymchurch Railway	Opened 1927
N	Norden	Swanage Railway	Original code
NX	Norden	Swanage Railway			Future code when level crossing commissioned
N	North	Mizens Railway	Controlled signals
B					Shunt signals
X					Track circuit controlled signals
NW	North Weald	Epping Ongar Railway
T	North Weald	Epping Ongar Railway			Training signal beside sidings
ON	Okehampton	Dartmoor Railway	Training signal
OO	Old Oak	Spinney Light Railway
OW	Old Works	Crewe Heritage Centre miniature railway	Longer ride with reversal near entrance
OG	Ongar	Epping Ongar Railway
VO	Orchard Green Junction	Isle of Wight Railway	Museum demonstration signal, removed by August 2019
AF	Orchard Green Junction	Isle of Wight Railway			Original code ('April Fool'), soon replaced
PS	Paignton South	Paignton & Dartmouth Railway
PW	Pinesway Junction	Gartell Light Railway
S		Pinewood Railway, Wokingham
C S		Pinewood Railway, Wokingham
RG	Prospect Park	Reading Society of Model Engineers	Ground level line
RR	Prospect Park	Reading Society of Model Engineers			Raised level line
QP	Queens Park	Paignton & Dartmouth Railway
RKHL	Rainsbrook	Rainsbrook Park, Rugby	High level line
RKLL	Rainsbrook	Rainsbrook Park, Rugby			Low level line
R	Robertsbridge	Kent & East Sussex Railway	Applied to at least one ground shunt signal
WJ	Rugby	Signalling Engineering School & Technical Assessment Centre (GM Rail Services)	Training signal: 33 Somers Road, Rugby site
GM	Rugby				Training signal: 65 Somers Road, Rugby site
ED	Slateford	Slateford Signalling School (on site of Slateford Junction)	Training signal
KS	Slateford	Slateford Signalling School (on site of Slateford Junction)	Training signal
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	Stoke Park	Guildford Miniature Railway
SPA	Stoke Park	Guildford Miniature Railway			Automatic signals
SP	Sutton	Sutton Life Educational Centre	Track safety simulator signal
T	Thuxton	Mid-Norfolk Railway
TE	Tunnel East	Beer Heights Light Railway	Also referred to as T'Other End
T	Twitchen Manor	Mizens Railway	Controlled signals
A					Shunt signals
X					Track circuit controlled signals
NR	Walsall	Network Rail training school	Training signal
EH		West Ashfield (London Underground training 'station' in West Kensington)	Training signal
WB	Willowbank	Malden & District Society of Model Engineers
W	Willowbank	Malden & District Society of Model Engineers			Code reported but possibly not carried
W	Winchcombe	Gloucestershire Warwickshire Railway	Unclear whether code actually carried

Signal box prefix codes

A (hopefully) comprehensive listing

Non-national rail codes

Croydon Tramlink signals

Docklands Light Railway signals

Edinburgh Tramway signals