Question: What was the main development in this central district in the 17th century in SW postcode area , which has the post code SW1A ?

text: SW postcode area
Postal administration -- List of postcode districts
The approximate coverage of the postcode districts , with the historic postal district names shown in italics : [ 5 ]
The SW (South Western) postcode area, also known as the London SW postcode area, is a group of postcode districts covering a broad radial swathe of southwest London, England as far as Mortlake, Streatham and Raynes Park. The area straightforwardly succeeds a shorter-lived South Western (SW1-SW10) and Battersea (SW11-SW20) split between its components of the London post town.
Postcode district Post town Coverage Local authority area
SW1A LONDON Whitehall , Buckingham Palace , the Houses of Parliament and west of St James 's Westminster
SW1E LONDON Northern 'Victoria ' around Buckingham Gate ( a street ) to include both sides of part of Victoria Street Westminster
SW1H LONDON Surrounds of St James 's Park tube station centred on Broadway , Queen Anne 's Gate and Old Queen Street to include both sides of part of Victoria Street - derivation : Horse Guards Parade Westminster
SW1P LONDON A projection around Parliament Square . Nearby Westminster School to Westminster Cathedral to CCAL , University of the Arts , London ( omitting all backstreets nearest to Vauxhall Bridge Road ) - derivation : Parliament Square Westminster
SW1V LONDON between Vauxhall Bridge , Grosvenor ( or Victoria Railway ) Bridge and Victoria Station , taking in both sides of Vauxhall Bridge Road ; includes Pimlico Westminster
SW1W LONDON South or lower Belgravia and Chelsea ( a corner ) , from Sloane Square to Victoria Station to Grosvenor Waterside basin Westminster , Kensington and Chelsea
SW1X LONDON Rest of Belgravia ( north of Eaton Square ) , Knightsbridge ( eastern half ) and Chelsea ( a corner ) Westminster , Kensington and Chelsea
SW1Y LONDON All but the west of St James 's Westminster
SW2 LONDON Brixton district : Brixton Hill , Tulse Hill ( part ) , Brixton ( part ) , Streatham Hill , Clapham ( part ) , Eastern parts of Balham , Lambeth Lambeth
SW3 LONDON Chelsea district : Chelsea , Brompton , Knightsbridge ( part ) Kensington and Chelsea
SW4 LONDON Clapham district : Clapham , Stockwell ( part ) Lambeth , Wandsworth
SW5 LONDON Earls Court district : Earls Court Kensington and Chelsea
SW6 LONDON Fulham district : Fulham , Parsons Green Hammersmith and Fulham
SW7 LONDON South Kensington district : South Kensington , Knightsbridge ( part ) Kensington and Chelsea , Westminster
SW8 LONDON South Lambeth district : South Lambeth , Wandsworth Road , Vauxhall , Battersea : Nine Elms ( part ) , Clapham ( part ) , NW area of Stockwell , Oval ( part ) Lambeth , Wandsworth
SW9 LONDON Stockwell district : Brixton , Stockwell , Clapham ( part ) , Oval ( part ) Lambeth
SW10 LONDON West Brompton district : West Brompton , Chelsea ( part ) Kensington and Chelsea , Hammersmith and Fulham
SW11 LONDON Battersea head district : Battersea , Clapham South Wandsworth , Lambeth
SW12 LONDON Balham district : Balham , Clapham South , Wandsworth Common ( part ) Wandsworth , Lambeth
SW13 LONDON Barnes district : Barnes Richmond upon Thames