Signal box prefix codes

A (hopefully) comprehensive listing

'Boxes beginning A

Last update 17 June 2025

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:

Code Signal Box Note ELRMileage Opened Closed Control to
AF Abbey Foregate Junction WSJ2171m 13ch 1914
AJ Abbey Junction NWO9m 64ch 1867? 16 February 1992 Nuneaton (NN)
R Repeater signals
AW Abbey Wood Downgraded to gate box 25 October 1970 NKL11m 49ch ≈1874 13 July 1975 Dartford (D)
AE Abbey Works East OVE2m 40ch 20 March 1949 1 November 1987 Port Talbot (PT)
AW Abbey Works West OVE1m 74ch 20 March 1949 4 July 1982 Port Talbot (PT)
AG Aberbeeg Junction EBW14m 21ch November 1891 14 December 1997 Park Junction (PJ)
Abercwmboi ABD21m 22ch by 1884 9 October 1989 Abercynon (A, AB)
A Abercynon Aberdare branch signals. Code used by 4 September 1977 CAM16m 25ch 3 April 1932 30 May 2008 Abercynon [new] (A)
AB Merthyr Tydfil branch signals
A Abercynon [new] CAM16m 25ch 30 May 2008 2 May 2023 Core Valley Lines Integrated Control Centre (VA)
AS Aberdare Sidings Ground Frame MLN1 10 September 1966 Old Oak Common (OO)
A Aberdeen Code used from 1981 ECN5240m 63ch 21 June 1981
A Aberdour Code used 1979 ECN217m 34ch 1890 10 December 1979 Edinburgh (EU)
A Abergavenny Also known as Abergavenny Station and as Abergavenny (Monmouth Road) Station HNL122m 75ch 27 May 1934 Wales Rail Operating Centre (NS) (planned)
AY
Abergavenny (Monmouth Road) See Abergavenny
Abergavenny Station See Abergavenny
AE Abergele CNH3213m 29ch August 1902 late on 23 March 2018✖last train; official closure 26 March 2018 Wales Rail Operating Centre (FH)
AW Aberthaw Formerly named Aberthaw East VOG5m 03ch November 1897 9 March 2013✖delayed from 28 January 2013 South Wales Control Centre (CF)
A Some signals shown on signal plan
Aberthaw East See Aberthaw
A Abington Code used from 1972 WCM157m 53ch 20 September 1942 29 April 1973 Motherwell (MC)
A Acklington ECM7≈28m 36ch 11 January 1964 Chevington (CN)
R Two emergency aerodrome signals. Code used by 1954
A Acle NAY10m 29ch 1882 17 February 2020 Colchester [new] (YL)
A Acton Formerly named Acton West MLN14m 79ch 1 September 1932 24 February 1968 Old Oak Common [new panel] (OO)
DM Down main line automatic signals
AB Acton Bridge CGJ1172m 35ch 25 June 1972 Winsford (WD)
ACW Acton Canal Wharf CAW8m 40ch 1895
AG Acton Grange CGJ2≈180m 12ch 5 April 1940 16 September 1972 Warrington (WN)
AL Acton Lane LLG0m 30ch 10 May 1964 24 December 2000 Wembley (WM)
AM Acton Middle MLN14m 25ch 1900 31 January 1959 Acton (A)
AW Acton Wells Junction BOK50m 65ch 1892
AW Acton West MLN1≈4m 65ch 5 May 1984 Old Oak Common [new panel] (OO)
Acton West See Acton
AY Acton Yard MLN14m 16ch 1 February 1959 7 April 1984 Old Oak Common [new panel] (OO)
AC Addiscombe Burnt down 7 March 1996; code not carried on signals EEA12m 66ch 1899 31 May 1997 Line closed
AD Addlestone Downgraded to gate box 22 March 1970 VWW20m 64ch 1899 6 January 1974 Woking ASC (WV)
A Adwick Crossing Code used from 1980 PED414m 47ch ≈1907 10 May 1981 Sheffield (S)
AX Earlier code
A Adwick Junction DOL1160m 57ch 1958 8 March 1970 Skellow (S)
AJ Agecroft Junction MVE13m 33ch November 1950 9 April 1988 Windsor Bridge (WB)
Ainsdale HXS314m 67ch 1878 11 March 1994 Merseyrail (ML)
AD Airdrie Code used from 30 July 1960 NEM210m 38ch 28 February 1960 28 July 1991 Yoker (YS)
AN Albion Downgraded to shunt frame 8 January 1966: line controlled by Birmingham New Street (NS) RBS26m 14ch Birmingham New Street (NS)
A Aldam Junction PED39m 76ch 24 November 1906 5 March 1983 Line closed
AJ
AS Aldershot Named Aldershot A to 3 April 1977 PAA134m 75ch ≈1900 27 August 2013 Woking ASC (WK)
ASA Semi-automatic signals partially controlled from Ground Frame A
WAS Automatic signals (code not seen on site: possibly should be WA500-series automatic signals)
WA Automatic signals
Aldershot A See Aldershot
Aldershot Junction See Aldershot Junction North
GW Aldershot Junction North PAA133m 40ch 1879 23 August 1970 Aldershot (AS)
AJ Aldridge Junction CBR2 May 1967? Walsall (WL)
A Aldwarke Junction TJC3 WME164m 46ch 6m 75ch 7 March 1965 25 February 1980 Sheffield (SA)
RA Repeater signals
SA Temporary code (post 1979?) until taken over by Sheffield
SA Aldwarke Junction [reopened] TJC3 WME164m 46ch 6m 75ch 23 September 1990 11 July 1992 Sheffield (SA)
AD Alexandra Dock KGD Line closed
AX Alexandria BCH19m 20ch 11 March 1973 Yoker (YD)
AD Allerton Depot Stop boards
AN Allerton Junction WJL3187m 66ch 8 August 1960 24 December 2018✖last train; official closure 2 January 2019 Manchester Rail Operating Centre (WE)
ANR Banner repeater signals
AJ Code reported in June 1993 weekly notice
AL Allington NOG1108m 72ch 3 October 2005
AJ Allington Junction NOG1108m 71ch 12 May 1875 30 September 2005✖last train; official closure 3 October 2005 Allington (AL)
A
AT Allscott Sugar Works Code possibly not carried WSJ2164m 33ch 5 February 1928 27 January 1985 Wellington (WN)
D Alne Down line semi-automatic signals ECM5≈11m 14ch 15 May 1960 Pilmoor (P)
U Up line semi-automatic signals
A Alnmouth Named Alnmouth North to 1957 Code used from 1977 replacing all others ECM734m 76ch 1907
AH Code used to 1977
D Down line automatic signals
U Up line automatic signals
Alnmouth North See Alnmouth
Alresford Station Downgraded to gate box 21 December 1958: line controlled by East Gate Junction (EG) COC57m 68ch 1889 2 March 2009 Colchester [new] (CO)
AS Alrewas BJW322m 10ch 1899
GA Alstone See Cheltenham Alstone
A Altofts Junction Code used by December 1977 TJC3186m 00ch 5 June 1927 2 March 1990 Altofts Junction [new] (AJ)
AJ
RAJ Repeater signals
AJ Altofts Junction [new] NOC TJC323m 57ch 186m 00ch 3 March 1990 20 September 1997 Castleford (CD)
AM Altrincham CDM17m 61ch 7 July 1991✖full replacement signalling into use 22 July 1991 Deansgate Junction (DJ)
AY Amberley TBH154m 61ch 24 January 1934 17 March 2014✖last train; official closure delayed from 25 October 2013 Three Bridges [new] (T)
AR Ancaster GRS2114m 48ch 1 December 1873
WFN Andover A Named Andover Junction A to 7 August 1964 BAE166m 11ch 1882 2 December 1973 Basingstoke [panel] (YW)
WFO Andover B Named Andover Junction B to 7 August 1964 Code used from 25 April 1968 BAE166m 30ch 1882 2 December 1973 Basingstoke [panel] (YW)
DWFO Distant signals
WA Automatic signals
Andover Junction A See Andover A
Andover Junction B See Andover B
AR Angel Road BGK 10 March 1969 Liverpool Street (L)
AG Angmering BLI115m 48ch 1877 25 June 1988 Lancing (LG)
A Anlaby Road HUL10m 73ch ≈October 1964 Hessle Road Junction (HR)
AN Annan Code used from 1973 GSW107m 10ch 1876
A Unclear if code carried
AN Annat Downgraded to gate box 6 December 1987: line controlled by Banavie (B) MLG22m 15ch 21 June 1964 23 October 2011 Banavie (B)
ANT Unclear if code carried
A Apperley Junction TJC3202m 03ch 27 November 1927 4 July 1994 Leeds (L)
AJ
A Appleby (Lincolnshire) DOW26m 59ch 1885 24 February 2003 Appleby (Lincolnshire) [temporary panel]
AY Appleby (Lincolnshire) [temporary panel] DOW26m 58ch 24 February 2003 19 December 2004 Appleby (Lincolnshire) [reopened] (AY)
AY Appleby (Lincolnshire) [reopened] Reopened original 'box following rebuilding DOW26m 59ch 19 December 2004 30 December 2015 York Rail Operating Centre (BD)
A Appleby North Original code SAC277m 34ch 1951 18 November 2019 Kirkby Thore (KT) temporarily during structural repairs
AN Code believed used from 8 December 2008
A Appleby North [reopened] SAC277m 34ch 13 January 2020
AN Code believed used
AP Appledore ATH64m 46ch 27 June 1954 6 November 1995 Ashford IECC (AD)
AX Appleford Downgraded to gate box 17 May 1965: line controlled by Swindon B (SB). Now demolished. Signal plan states Controlled and supervised by dedicated crossing controller's panel at Swindon SCC. DCL54m 54ch 1952 27 May 2001 Swindon B (SB)
A Code used as gate box
AT Applehurst Junction Code used by 3 May 1970 CJS163m 26ch 1 July 1877 29 June 1980 East Midlands Control Centre (D)
AJ Code used from 6 September 1970?
AH Arbroath Named Arbroath North to 21 March 1971 Code used from 2002 ECN316m 59ch 26 March 1911
Arbroath North See Arbroath
Arch Junction See Archcliffe Junction
ZE Archcliffe Junction Sometimes also known as Arch Junction (possibly in error) XTD76m 42ch 3 June 1928 10 April 1998 Folkestone East (YE)
A Ardleigh LTN155m 77ch by 1893 24 April 1983 Colchester [new] (CO)
AE Ardmore East Code used from 1960 NEM721m 14ch 24 January 1943 12 December 1976 Craigendoran (CN)
AW Ardmore West NEM721m 69ch 28 February 1943 4 November 1973 Ardmore East (AE)
AS Ardsley Station DOL1180m 11ch 1870 15 November 1970 Lofthouse North (LN)
U Up line automatic signals
A1 Ardwick No 1 HAJ0m 59ch 30 July 1905 28 October 1973 Manchester Piccadilly (MP)
A Arksey Code used probably from 1949. See also Doncaster ECM1158m 02ch 2 February 1872✖inspected 24 August 1878 26 October 1980 Doncaster (D)
A Arlesey ECM135m 51ch 1898 27 June 1976✖delayed from 13 June 1976 Hitchin (HT)
AY Arley NWO4m 60ch 9 August 1969 Saltley (SY)
AE Armitage LEC2122m 09ch 12 June 2005? Colwich (CH)
AE Arnside Code used from 2008 CBC16m 29ch 1897?
Plans made for Carnforth-Arnside, with all Carnforth boxes and line to Wennington closed, showed AE signals at Silverdale, believed never installed
AJ Arpley Junction SDJ211m 03ch WOA10m 00ch 1918
A Arthington Temporary 'box for tunnel repair work LEH118m 48ch 30 June 1980 31 May 1981 Horsforth (H)
AR Repeater signals
AR Arundel Code used from 22 November 1979 TBH158m 36ch 27 March 1938
CBV Code used to 22 November 1979 when new panel installed
AJ Arundel Junction Code carried on one signal only (AJ6), 22 November 1979 to 8 December 1979 BLI119m 01ch TBH159m 75ch TBH219m 01ch 28 September 1885 8 December 1979 Arundel (AR)
CA Automatic signals
F Ascot Named Ascot B to 19 May 1974 RDG129m 13ch 16 October 1938 8 September 1974 Feltham (F)
Ascot B See Ascot
AW Ascott under Wychwood Code used by 1973 OWW80m 37ch 1883
AY Asfordby GSM4111m 40ch
A Code used by 29 January 1995
X Draw ahead signals
MT Asfordby (Rail Innovation & Development Centre control point) ERTMS block markers
AS Ashburys Named Ashburys East to May 1984 Code used from renaming HAJ1m 56ch 1906 18 September 2011 Manchester East Signalling Control Centre (AS)
AE Code used when named Ashburys East
Ashburys East See Ashburys
AW Ashburys West Junction HAJ1m 27ch 13 July 1905 6 May 1984 Ashburys (AS)
NN Ashby Junction Temporary code from 10 November 1962 until taken over by Nuneaton LEC297m 57ch ≈1963✖definitely by 1972 Nuneaton (NN)
FW Ash Crossing GTW249m 15ch 13 February 1966 30 October 1998 Guildford Area Signalling Centre (GD)
WA Automatic signals
RWA Repeater to automatic signals
UE Ashford XTD56m 23ch 29 April 1962 10 December 1995 Ashford IECC (AD)
A Automatic signals
D Distant signals
AF Ashford Centre CTRL control centre, located within Ashford IECC TRL390.550km XTD56m 21ch 2003
D Down line automatic signals and stop/ proceed markers
DC Automatic signals and stop/ proceed markers on Stratford International-Temple Mills connecting line
DW Automatic signals and stop/ proceed markers on Down Waterloo connection
U Up line automatic signals and stop/ proceed markers
UW Automatic signals and stop/proceed markers on Up Waterloo connection
H Ashford Depot Code derived from 'Hitachi' (depot operators) ACR 2 October 2007✖depot formal opening date
AD Ashford IECC XTD56m 21ch 21 February 1993✖main IECC; North Kent lines added in stages 2000-2001
A Automatic signals. Unclear whether code exists
R Banner repeater signals
NK North Kent area (VDU based control and indication system)
WBL Ashford [Middx/Surrey] RDG117m 48ch 23 February 1930 8 September 1974 Feltham (F)
A Ashington Junction BWC3m 02ch 1896 14 February 2010 Marcheys House (MH)
Ashington Loop No 1 See Ashington NCB No 1 Loop
A Ashington NCB No 1 Loop Also known as Ashington Loop No1 BWO1 5 April 1987✖delayed from 31 March 1987 Ashington Junction (A)
A Ashley Hill Unclear if code used BSW2m 61ch 5 July 1925 17 October 1970 Bristol (B)
CBG Ashtead Downgraged to gate box 26 April 1964 BTH316m 13ch 28 November 1930 10 December 1978 Leatherhead (CBH)
Ashton Junction See Guide Bridge
AJ Ashton Junction [Bristol] Code used from 6 December 1971 POD121m 19ch 20 May 1906 1990✖out of use; burnt down 1994, official closure April 1999 Bristol (B)
AMN Ashton Moss North Junction Demolished by 17 April 2018 AMJ0m 29ch MVL15m 52ch 1911 14 April 2018✖last train; official closure 29 April 2018 Manchester Rail Operating Centre (MN)
AM Code not carried
AMS Ashton Moss South Junction DJO21m 29ch 1911 22 September 1991 Ashton Moss North Junction (AM)
HW Ash Vale Junction AAV40m 48ch 2 June 1879 27 August 2013 Woking ASC (WK)
WA Automatic signals
AL Ashwell GSM296m 66ch 30 June 1912
AM Askam CBC135m 03ch 1890
Askern Colliery had draw-ahead signals in colliery sidings lettered A to F, with no number KWS? Colliery closed
A Aslockton NOG1117m 29ch 21 December 1875 13 March 1977 Aslockton [gate box] (A)
A Aslockton [gate box] Gate box: line controlled by Bottesford West Junction (BW) NOG1≈117m 20ch 13 March 1977 29 November 1986 Bottesford West Junction (BW)
Aspatria CBC27m 74ch 1891 18 January 1998 Maryport Station (MS)
Aspley Guise BBM5m 04ch 6 September 2004 Marston Vale (MV)
AY Astley DSE22m 55ch? 1872 1972 Astley [new] (AY)
AY Astley [new] DSE22m 55ch 17 September 1972
Astley Bridge Temporary block post BBB11m 74ch 1 December 1985 7 December 1985 Bolton (BN)
AN Aston PBJ0m 37ch 12 October 1992 (in 1957 building)
AN Aston No 1 PBJ≈1m 55ch 2 July 1966 Birmingham New Street (NS)
AY Athelney Formerly named Athelney West CCL134m 77ch July 1906 5 April 1986 Exeter (E)
Athelney West See Athelney
AE Atherstone LEC2102m 23ch 10 November 1962 22 July 1990 Nuneaton (NN)
AG Atherton Goods Yard WBS111m 18ch 1956 29 July 2013✖delayed from 25 March 2013 Manchester Piccadilly (MP)
AH Attenborough Station TSN1≈121m 69ch 19 December 1969 Trent (TT)
A Attercliffe Road Station TJC1159m 23ch 25 April 1965 Brightside (B)
A Attleborough ETN108m 20ch 1883 2 December 2012 Cambridge (EN)
AB
AR Auchterarder Code used from 2002 SCM4137m 41ch 11 October 1895
AU Code reported but probably not used
Aughton Road HXS317m 49ch 1928 11 March 1994 Merseyrail (ML)
AS Avenue Sidings SPC9≈143m 30ch ≈1971 Trent (TT)
A Aviemore Code used to 2002 HGL283m 51ch 16 June 1898 26 March 2019✖official date; last train earlier Inverness (HA, HC, HK, HM, HS, HT)
AV Aviemore area. Code used from 2002 replacing A
AC Carrbridge interlocking. Code used from 1979
AK Kincraig interlocking. Code used from 1979
AM Moy interlocking. Code used from 1979
AS Slochd interlocking. Code used from 1979
AT Tomatin interlocking. Code used from 1980
AD Avonmouth Dock Junction CNX8m 28ch 24 July 1906 22 January 1988 St Andrews Junction [Bristol] (SA)
AJ Awre (Junction) Downgraded to gate box 2 June 1969. Apparently still extant and able to be used in emergencies SWM2128m 22ch March 1909 30 December 1973 Gloucester (G)
WDG Axe Gates Downgraded to gate box 10 June 1967 BAE2141m 56ch August 1949 6 August 1967 Chard Junction (C)
A Axminster Crossing Gate box in station building: line controlled by Chard Junction (C). Preceding gate box now preserved at private site BAE2144m 41ch 16 December 1973
Aylesbury South MCJ238m 02ch June 1908 24 November 1990 Marylebone [new] (ME)
AF Aylesford PWS238m 75ch 14 August 1921
Ayleston Hill See Hereford
AJ Aynho Junction DCL81m 03ch 4 April 1910 5 March 1992 Banbury South (BS)
GF Ayr Harbour ground frame AYH10m 21ch 22 January 1984
PA Ayr Local Signalling Panel See Paisley Ayr interlocking AYR639m 73ch 7 April 1985 1 June 1986 Paisley [new] (PA) (local control still possible)
A Code used to closure
A Ayton ECM850m 20ch 25 April 1943 25 February 1978 Edinburgh (EG)
D Down line automatic signals
RD Distant to down line automatic signals