London Transport Signal and IMR codes

London Underground Railways Signalling is a subject in its own right, and it can be a fascinating subject to follow up. The underground system is made up of the following LU Signal Box and IMR*s - Interlocking Machine Rooms.

Here are the codes for all London Transport lines at present, plus some past codes - most codes were just single letters originally and later began to be prefixed with another letter (usually the line initial) for more precise recognition - all codes in this list have been verified to be correct.

Bakerloo Line Queens Park - BB Paddington - BD Baker Street - BM Piccadilly Circus - BP Lambeth North - BR Elephant - BS	Victoria Line Brixton - VE Victoria - VF Warren Street - VG Kings Cross - VH Highbury - VJ Finsbury Park - VK Seven Sisters - VL Northumberland Park Depot - VN Walthamstow Ctrl - VP	Circle Line/Met codes 1904-1950's A - Praed Street (later Edgware Road) B - Baker Street C - King's Cross D - Farringdon E - Barbican F - Moorgate G - Liverpool Street H - Aldgate
Circle Line/H&C Codes 1950's-Present OB - Aldgate/Aldgate East OD - Liverpool Street OE - Moorgate OG - Barbican OH - Farringdon OJ - Kings Cross MB - Baker Street OP - Edgware Road OR - Paddington Suburban OS - Westbourne Park OU - Ladbroke Grove OZ - Hammersmith	Metropolitan Main Line (original codes) B - Baker Street D - Finchley Road E - Willesden Green F - Neasden G - Wembley Park H - Harrow South J - Harrow Main N - Harrow North P - Rayners Lane R - Eastcote V - Hillingdon W - Uxbridge Ruislip cannot be confirmed in this series.	Piccadilly Line - Original Codes (Present Codes) Codes west of Barons Court are under the District 'W-' series. A - Hammersmith Pic (WD from 1932) B - Down Street/Hyde Park Cnr (now PB) C - Covent Garden D - Holborn (now PD) E - York Road F - Finsbury Park (now VK) G - Wood Green (now PG) J - Arnos Grove (now PJ) K - Oakwood (now PK) M - Cockfosters (now PM)
Central Line (Pre-resignalling) West Ruislip CS Ruislip Gardens CS (subsiduary to West Ruislip) Northolt - CP Greenford - CL Ealing Bdy - WP (was L) North Acton - CJ White City - CG (was G) Shepherd's Bush - CF (was F) Queensway - CE (was E) Marble Arch - CD (was D) Holborn - CC (was C) Bank - was B Liverpool St - LB (was A) Bethnal Green - LC Stratford - LD Leyton - LE Leytonstone - LF Snaresbrook - LG South Woodford - LH Woodford - LJ Grange Hill subsiduary box to Hainault LL (unoffically LK) Hainault LL Fairlop - LM Barkingside - LN Newbury Park - LP Loughton - LT Debden - LU Theydon Bois - LV Epping - LW North Weald (until 1976) - LX Ongar - LX	District/Piccadilly codes west of Earls Court begun with W, those east beginning with E - those principles remain more or less today. WA - Earls Court West (now EC) WB - West Ken East/Olympia WC - West Ken West WD - Hammersmith WE - West Brompton WF - Parsons Green WG - Putney Bridge (WH) - Junction with LWSR at ravencscourt Park? WK - Turnham Green WL - Acton Town WM - Ealing Common (WN - Hanger Lane Jcn (WM from 1925)?) WP - Ealing Broadway WQ - South Acton WR - Northfields (WS - Boston Manor (until 1932)?) WT - Hounslow Central WU - North Ealing (closed) WV - South Harrow WW - Hatton Cross (was Sudbury Hill) WX Hounslow West (until 1975) WY - Heathrow EA - Earls Court East (now EC) EB - High St Ken (now ED) EC - Earls Court (was Cromwell Rd) ED - High St Ken (present) EE - Gloucester Road EF - South Kensington EG - St James Park (Closed) EH - Embankment EJ - Tower Hill (was mansion House) EK - Minories Junction (Now OB) EL - Aldgate East (Now OB) (EM - St Marys Jc until part of EN?) EN - Whitechapel EP - Bow Road (closed) ER - Surrey Quays ET - New Cross area B - Shoreditch/Whitechapel (ELL) OB - Aldgate East FB - Bromley FC - Plaistow FE - East Ham FF - Barking FG - Dagenham East FJ - Hornchurch FM - Upminster	Northern Line Original Series A - Kennington (when all autos prefixed S) B - Kennington (present) C - Charing Cross D - Mornington Crescent (until 1924) E - Camden Town/Mornington Cres (from 1924) F - Hampstead G - Golders Green J - Euston (+ Kings Cross from 1967) K - Angel L - Kings Cross (loop only from 1967) M - Moorgate P - London Bridge U - Stockwell T - Clapham Common W - Tooting Bdy Y - Morden Z - Morden Depot (not official) 1920's extension codes AA - Brent Cross AB - Hendon Central AC - Colindale AE - Edgware 1930's extension codes NC - Drayton Park/Finsbury Park ND - Moorgate (Northern City) NH - Park Junction (now Highgate Depot) NN - Archway NP - East Finchley NQ - Finchley Central/Mill Hill NS - Woodside Park NT - Totteridge NU - High Barnet NV - Mill Hill East (now NQ)
Metropolitan Main Line Present Series MB - Baker Street MD - Finchley Road (+W Hampstead until 1985, now JD) ME - Willesden Green (JE from 1985) MF - Neasden (now MM) MG - Wembley Park MH - Neasden Depot North End (closed) MK - Stanmore/Canons Park (JL from 1985) ML - Swiss Cottage MM - Neasden (present) MP - Rayners Lane MR - Eastcote MU - Ruislip MV - Hillingdon MW - Uxbridge JB - Harrow JD - Finchley Road/W Hampstead Jubilee (from 1985) JE - Willesden Green (from 1985) JF - Northwood (was Neasden) JG - Wembley Park Jubilee (1985) JJ - Watford South JL - Stanmore (from 1985) JP - Watford/Rickmansworth JT - Chalfont/Chesham JW - Amersham	Jubilee Line Stanmore - JL (MK until 1985) Canons Park - MK Wembley - JG (MG until 1985) Neasden - JF (MF until 1985) Willesden Green - JE (ME until 1985) West Hampstead/Finchley Rd - JD (MD until 1985) Baker Street - BM Green Park - TF Charing Cross - TG Waterloo - TH London Bridge - TJ Canada Water - TK Canary Wharf - TL North Greenwich - TM Southwark - TP Bermondsey - TR West Ham - TU Stratford Market Depot - TY Stratford - TW