UK Registration Numbers . . .
 
Where was your car first registered?  The last two letters preceding the numbers indicate the registering authority. e.g. CKN808 would have been registered in Kent.
 
Mark Authority   Mark Authority   Mark Authority
  A London    AA Southampton (County)    BA Salford
  B Lancashire C C    AB Worcestershire    BB Newcastle-upon-Tyne
  C Yorkshire West Riding    AC Warwickshire    BC Leicester
  D Kent C C    AD Gloucestershire    BD Northamptonshire
  E Staffordshire C C    AE Bristol C B C    BE Lincolnshire (Parts of Lindsey)
  F Essex C C    AF Cornwall C C    BF Dorsetshire C C
             BF Staffordshire C C
  G Glasgow    AG Ayr C C    BG Birkenhead C B C
  H Middlesex C C    AH Norfolk    BH Buckinghamshire C C
       AI Meath (County)    BI Monaghan
  J Durham C C    AJ Yorkshire North Riding    BJ [East] Suffolk
  J Jersey            
  K Liverpool C B C    AK Bradford C B C    BK Portsmouth
  L Glamorganshire C C    AL Nottinghamshire    BL Berkshire
  M Cheshire C C    AM Wiltshire    BM Bedfordshire
  N Manchester C B C    AN Isle of Man (MAN only)    BN Bolton C B C
       AN West Ham (exc MAN)      
  O Birmingham C B C    AO Cumberland C C    BO Cardiff C B C
  P Surrey C C    AP Sussex (East)    BP West Sussex
  R Derbyshire C C    AR Hertfordshire    BR Sunderland
  S Edinburgh B C    AS Nairn C C    BS Orkney
  T Devon C C    AT [Kingston upon] Hull    BT Yorkshire East Riding
  U Leeds C B C    AU Nottingham    BU Oldham
  V Lanark C C    AV Aberdeenshire    BV Blackburn C B C
  W Sheffield C B C    AW Shropshire    BW Oxfordshire
  X Northumberland C C    AX Monmouthshire    BX Carmarthenshire C C
  Y Somerset C C    AY Alderney    BY Croydon C B C
       AY Leicestershire C C      
  Z Dublin (County)    AZ Belfast C B C    BZ Down (County)
 
Mark Authority   Mark Authority   Mark Authority
 CA Denbighshire C C    DA Wolverhampton    EA West Bromwich
 CB Blackburn C B C    DB Stockport    EB [Isle of] Ely C C
 CC Caernarvonshire C C    DC Middlesbrough    EC Westmorland
 CD Brighton C B C    DD Gloucestershire    ED Warrington
       DD Northampton C B C      
 CE Cambridgeshire C C    DE Pembrokeshire    EE Grimsby
 CF [West] Suffolk    DF Gloucestershire    EF West Hartlepool
 CG Southampton County    DG Gloucestershire    EG [Soke of] Peterborough
 CH Derby C B C    DH Walsall    EH Stoke-on-Trent
 CI Laois    DI Roscommon    EI County Sligo
 CJ Herefordshire    DJ St.Helens (Lancs.)    EJ Cardiganshire C C
 CK Preston    DK Rochdale    EK Wigan
 CL Norwich    DL Isle-of-Wight    EL Bournemouth C B C
 CM Birkenhead C B C    DM Flintshire    EM Bootle C B C
 CN Gateshead    DN York    EN Bury C B C
 CO Plymouth    DO Lincolnshire (Holland)    EO Barrow-in-Furness C B C
 CP Halifax    DP Reading    EP Montgomeryshire
 CR Southampton    DR Plymouth    ER Cambridgeshire C C
 CS Ayrshire C C    DS Peebles    ES Perth
 CT Lincolnshire (Kesteven)    DT Doncaster    ET Rotherham
 CU South Shields    DU Coventry C B C    EU Brecknockshire C C
 CV Cornwall C C    DV Devon    EV Essex
 CW Burnley C B C    DW Newport (Mon)    EW Huntingdonshire
 CX Huddersfield    DX Ipswich    EX [Great] Yarmouth
 CY Scilly Isles (SCY only)            
 CY Swansea    DY Hastings    EY Anglesey C C
 CZ Belfast C B C    DZ [County] Antrim    EZ Belfast C B C
 
Mark Authority   Mark Authority   Mark Authority
 FA Burton-on-Trent C B C    GA Glasgow    HA Smethwick
 FB Bath    GB Glasgow    HB Merthyr Tydfil
 FC Oxford C B C    GC London    HC Eastbourne
 FD Dudley C B C    GD Glasgow    HD Dewsbury
 FE Lincoln    GE Glasgow    HE Barnsley C B C
 FF Merioneth    GF London    HF Wallasey
 FG Fife    GG Glasgow    HG Burnley C B C
 FH Gloucester    GH London    HH Carlisle C B C
 FI Tipperary (N.Riding)    GI Tipperary (S.Riding)    HI Tipperary (S.Riding)
 FJ Exeter    GJ London    HJ Southend-on-Sea
 FK Worcester    GK London    HK Essex
 FL [Soke of] Peterborough    GL Bath    HL Wakefield
 FM Chester C B C    GM Motherwell and Wishaw    HM East Ham
 FN Canterbury C B C    GN London    HN Darlington C B C
 FO Radnorshire    GO London    HO Hampshire
 FP Rutland    GP London    HP Coventry C B C
 FR Blackpool C B C    GR Sunderland    HR Wiltshire
 FS Edinburgh    GS Perth    HS Renfrewshire
 FT Tynemouth    GT London    HT Bristol C B C
 FU Lincolnshire (Lindsey)    GU London    HU Bristol C B C
 FV Blackpool C B C    GV [West] Suffolk    HV East Ham
 FW Lincolnshire (Lindsey)    GW London    HW Bristol C B C
 FX Dorset    GX London    HX Middlesex
 FY Southport    GY London    HY Bristol C B C
 FZ Belfast C B C    GZ Belfast C B C    HZ Tyrone
 
Mark Authority   Mark Authority   Mark Authority
 IA [County] Antrim    JA Stockport    KA Liverpool
 IB Armagh C C    JB Berkshire    KB Liverpool
 IC [County] Carlow    JC Caernarvonshire C C    KC Liverpool
 ID [County] Cavan    JD West Ham    KD Liverpool
 IE [County] Clare    JE [Isle of Ely] C C    KE Kent
 IF [County] Cork    JF Leicester    KF Liverpool
       JG Canterbury C B C    KG Cardiff C B C
 IH [County] Donegal    JH Hertfordshire    KH Kingston-upon-Hull
       JI Tyrone    KI [County] Waterford
 IJ [County] Down    JJ London    KJ Kent
 IK [County] Dublin    JK Eastbourne    KK Kent
 IL Fermanagh    JL Lincolnshire (Holland)    KL Kent
 IM [County] Galway    JM Westmorland    KM Kent
 IN [County] Kerry    JN Southend-on-Sea    KN Kent
 IO [County] Kildare    JO Oxford C B C    KO Kent
 IP [County] Kilkenny    JP Wigan    KP Kent
 IR Offaly    JR Northumberland    KR Kent
 IS [County] Mayo    JS Ross & Cromarty    KS Roxburgh
 IT Leitrim    JT Dorset    KT Kent
 IU [County] Limerick    JU Leicestershire C C    KU Bradford C B C
 IV [County] Limerick    JV Grimsby    KV Coventry C B C
 IW [County] Londonderry    JW Wolverhampton    KW Bradford C B C
 IX [County] Longford)    JX Halifax    KX Buckinghamshire C C
 IY Louth (County)    JY Plymouth    KY Bradford C B C
 IZ [County] Mayo    JZ Down    KZ Antrim
 
Mark Authority   Mark Authority   Mark Authority
 LA London    MA Cheshire C C    NA Manchester
 LB London    MB Cheshire C C    NB Manchester
 LC London    MC Middlesex    NC Manchester
 LD London    MD Middlesex    ND Manchester
 LE London    ME Middlesex    NE Manchester
 LF London    MF Middlesex    NF Manchester
 LG Cheshire C C    MG Middlesex    NG Norfolk
 LH London    MH Middlesex    NH Northampton
 LI Westmeath (County)    MI [County] Wexford    NI [County] Wicklow
 LJ Bournemouth C B C    MJ Bedfordshire    NJ [East] Sussex
 LK London    MK Middlesex    NK Hertfordshire
 LL London    ML Middlesex    NL Northumberland
 LM London    MM Middlesex    NM Bedfordshire
 LN London    MN Isle of Man    NN Nottinghamshire
 LO London    MO Berkshire    NO Essex
 LP London    MP Middlesex    NP Worcestershire
 LR London    MR Wiltshire    NR Leicestershire C C
 LS Selkirk    MS Stirling    NS Sutherland
 LT London    MT Middlesex    NT Shropshire
 LU London    MU Middlesex    NU Derbyshire
 LV Liverpool    MV Middlesex    NV Northamptonshire
 LW London    MW Wiltshire    NW Leeds
 LX London    MX Middlesex    NX Warwickshire
 LY London    MY Middlesex    NY Glamorganshire
 LZ Armagh C C    MZ Belfast C B C    NZ Londonderry
 
Mark Authority   Mark Authority   Mark Authority
 OA Birmingham C B C    PA Surrey    QA Foreign Visitors
 OB Birmingham C B C    PB Surrey    QB Foreign Visitors
 OC Birmingham C B C    PC Surrey    QC Foreign Visitors
 OD Devon    PD Surrey    QD Foreign Visitors
 OE Birmingham C B C    PE Surrey    QE Foreign Visitors
 OF Birmingham C B C    PF Surrey    QF Foreign Visitors
 OG Birmingham C B C    PG Surrey    QG Foreign Visitors
 OH Birmingham C B C    PH Surrey    QH Foreign Visitors
 OI Belfast C B C    PI Cork      
 OJ Birmingham C B C    PJ Surrey    QJ Foreign Visitors
 OK Birmingham C B C    PK Surrey    QK Foreign Visitors
 OL Birmingham C B C    PL Surrey    QL Foreign Visitors
 OM Birmingham C B C    PM East Sussex    QM Foreign Visitors
 ON Birmingham C B C    PN East Sussex    QN Foreign Visitors
 OO Essex    PO West Sussex      
 OP Birmingham C B C    PP Buckinghamshire C C    QP Foreign Visitors
             QQ Foreign Visitors
 OR Southampton (County)    PR Dorset      
 OS Wigtown    PS Zetland (Shetland)    QS Foreign Visitors
 OT Southampton (County)    PT [County] Durham    QT Foreign Visitors
 OU Southampton (County)    PU Essex      
 OV Birmingham C B C    PV Ipswich      
 OW Southampton    PW Norfolk      
 OX Birmingham C B C    PX West Sussex    QX Foreign Visitors
 OY Croydon C B C    PY Yorkshire North Riding    QY Foreign Visitors
 OZ Belfast C B C    PZ Belfast C B C      
 
Mark Authority   Mark Authority   Mark Authority
 RA Derbyshire    SA Aberdeen County    TA Devon
 RB Derbyshire    SB Argyll    TB Lancashire
 RC Derby C B C    SC Edinburgh    TC Lancashire
 RD Reading    SD Ayrshire C C    TD Lancashire
 RE Staffordshire    SE Banff    TE Lancashire
 RF Staffordshire    SF Edinburgh    TF Lancashire
 RG Aberdeen B C    SG Edinburgh    TG Glamorganshire
 RH [Kingston upon] Hull    SH Berwick    TH Carmarthenshire C C
 RI Dublin    SI Dublin C C    TI Limerick (Borough)
 RJ Salford    SJ Bute C C    TJ Lancashire
 RK Croydon C B C    SK Caithness C C    TK Dorset
 RL Cornwall C C    SL Clackmannan    TL Lincolnshire (Kesteven)
 RM Cumberland C C    SM Dumfries    TM Bedfordshire
 RN Preston    SN Dunbarton    TN Newcastle-upon-Tyne
 RO Hertfordshire    SO Moray    TO Nottingham
 RP Northamptonshire    SP Fife    TP Portsmouth
 RR Nottinghamshire    SR Angus C C    TR Southampton
 RS Aberdeen B C    SS [East] Lothian    TS Dundee
 RT [East] Suffolk    ST Inverness    TT Devon
 RU Bournemouth C B C    SU Kincardine    TU Cheshire C C
 RV Portsmouth    SV Kinross    TV Nottingham
 RW Coventry C B C    SW Kirkcudbright    TW Essex
 RX Berkshire    SX [West] Lothian    TX Glamorganshire
 RY Leicester    SY Midlothian    TY Northumberland
 RZ Antrim    SZ Down    TZ Belfast C B C
 
Mark Authority   Mark Authority   Mark Authority
 UA Leeds    VA Lanark    WA Sheffield
 UB Leeds    VB Croydon C B C    WB Sheffield
 UC London    VC Coventry C B C    WC Essex
 UD Oxfordshire    VD Lanark    WD Warwickshire
 UE Warwickshire    VE Cambridgeshire C C    WE Sheffield
 UF Brighton C B C    VF Norfolk    WF Yorkshire East Riding
 UG Leeds    VG Norwich    WG Stirling
 UH Cardiff C B C    VH Huddersfield    WH Bolton C B C
 UI Londonderry          WI Waterford
 UJ Shropshire    VJ Herefordshire    WJ Sheffield
 UK Wolverhampton    VK Newcastle-upon-Tyne    WK Coventry C B C
 UL London    VL Lincoln    WL Oxford C B C
 UM Leeds    VM Manchester    WM Southport
 UN Denbighshire C C    VN Yorkshire North Riding    WN Swansea
 UO Devon    VO Nottinghamshire    WO Monmouthshire
 UP [County] Durham    VP Birmingham C B C    WP Worcestershire
 UR Hertfordshire    VR Manchester    WR Yorkshire West Riding
 US Govan B C    VS Greenock    WS Leith
 US Glasgow          WS Edinburgh
 UT Leicestershire C C    VT Stoke-on-Trent    WT Yorkshire West Riding
 UU London    VU Manchester    WU Yorkshire West Riding
 UV London    VV Northampton    WV Wiltshire
 UW London    VW Essex    WW Yorkshire West Riding
 UX Shropshire    VX Essex    WX Yorkshire West Riding
 UY Worcestershire    VY York    WY Yorkshire West Riding
 UZ Belfast C B C    VZ Tyrone    WZ Belfast C B C
 
Mark Authority   Mark Authority   Mark Authority
 XA London    YA Somerset    ZA Dublin
 XB London    YB Somerset    ZB Cork
 XC London    YC Somerset    ZC Dublin
 XD London    YD Somerset    ZD Dublin
 XE London    YE London    ZE Dublin
 XF London    YF London    ZF Cork
 XG Middlesbrough    YG Yorkshire West Riding    ZG Dublin CC
 XH London    YH London    ZH Dublin
 XI Belfast C B C    YI Dublin    ZI Dublin
 XJ Manchester    YJ Dundee    ZJ Dublin
 XK London    YK London    ZK Cork
 XL London    YL London    ZL Dublin
 XM London    YM London    ZM Galway
 XN London    YN London    ZN Meath
 XO London    YO London    ZO Dublin
 XP London    YP London    ZP [County] Donegal
 XR London    YR London    ZR Wexford
       YS Glasgow    ZS Dublin CC
 XS Paisley    YS Partick B C      
 XT London    YT London    ZT Cork
 XU London    YU London    ZU Dublin
 XV London    YV London    ZV Re registrations
 XW London    YW London    ZW Kildare
 XX London    YX London    ZX [County] Kerry
 XY London    YY London    ZY Louth
 XZ Armagh C C    YZ Londonderry    ZZ Royal Irish Automobile Club, AA