All London postcodes are alphabetical apart from WC and EC areas. Also, the 1 postcodes (W1, E1 etc.) aren't alphabetical. Some areas, like N, just run from A ~ Z whilst others, such as SW, have two runs from A~ Z. The list, with a few missing spaces which cannot be explained, is;
SW2 Brixton SW3 Chelsea SW4 Clapham SW5 Earl's Court SW6 Fulham SW7 Knightsbridge SW8 Nine Elmes SW9 Stockwell SW10 World's End SW11 Battersea SW12 Balham SW13 Barnes SW14 East Sheen SW15 Putney SW16 Streatham SW17 Tooting SW18 Wandsworth SW19 Wimbledon SW20 Wimbledon Chase
NW2 Cricklewood NW3 Hampstead NW4 Hendon NW5 Kentish Town
NW6 Kilburn NW7 Mill Hill NW8 St John's Wood NW9 West Hendon
NW10 Willesden NW11 Willifield Green
W3 Acton W4 Chiswick W5 Ealing W6 Hammersmith W7 Hanwell
W8 Kensington W9 Maida Vale W10 North Kensington W11 Notting Hill W12 Shepherd's Bush W13 West Ealing W14 West Kensington
SE2 Abbey Wood SE3 Blackheath SE4 Brockley SE5 Camberwell SE6 Catford SE7 Charlton SE8 Deptford SE9 Eltham SE10 Greenwich SE11 Kennington SE12 Lee SE13 Lewisham SE14 New Cross SE15 Peckham SE16 Rotherhithe SE17 Walworth SE18 Woolwich Arsenal SE19 SE20 Anerley SE21 Dulwich SE22 East Dulwich SE23 Forest Hill SE24 Hearne Hill SE25 South Norwood SE26 Sydenham SE27 West Norwood SE28 Woolwich & Thamesmead
E2 Bethnal Green E3 Bow E4 Chingford E5 Clapton E6 East Ham E7 Forest Gate E8 Hackney E9 Homerton E10 Leyton E11 Leytonstone E12 Manor Park E13 Plaistow E14 Poplar E15 Stratford E16 Victoria Dock E17 Walthamstow E18 Woodford
N2 East Finchley N3 Finchley N4 Finsbury Park N5 Highbury N6 Highgate N7 Holloway N8 Hornsey N9 Lower Edmonton N10 Muswell Hill N11 New Southgate N12 North Finchley N13 Palmers Green N14 Southgate N15 Stamford Hill N16 Stoke Newington N17 Tottenham N18 Turnpike Lane N19 Upper Holloway N20 Whetstone N21 Winchmore Hill N22 Wood Green
Christ...I need to get out more!