Postcode district boundaries: Bing / Google
The SW (South Western and Battersea) postcode area, also known as the London SW postcode area, is a group of postcode districts covering part of southwest London, England. The area originates from the South Western (SW1–SW10) and Battersea (SW11–SW20) districts of the London post town.
The postcode area originated in 1857 as the SW district. In 1868 it gained some of the area of the abolished S district, with the rest going to SE. It was divided into numbered districts in 1917. The South Western district consists of the postcode districts SW1–SW10 and the Battersea district consists of the postcode districts SW11–SW20.
The approximate coverage of the postcode districts, with the historic postal district names shown in italics:
SW1 was originally the South Western head district. As it is now of very high density development it has been divided into smaller postcode districts. Where districts are used for purposes other than the sorting of mail, such as use as a geographic reference and on street signs, the SW1 subdivisions continue to be classed as one 'district'. Within the SW1 postcode district there are several distinctive postcode units:
For the purposes of directing mail, the United Kingdom is divided by Royal Mail into postcode areas. The postcode area is the largest geographical unit used and forms the initial characters of the alphanumeric UK postcode. There are currently 121 geographic postcode areas in use in the UK and a further 3 often combined with these covering the Crown Dependencies of Guernsey, Jersey and Isle of Man.
Each postcode area is further divided into post towns and postcode districts. There are on average 20 postcode districts to a postcode area. The London post town is instead divided into several postcode areas.
The single or pair of letters chosen for postcode areas are generally intended as a mnemonic for the places served. Postcode areas, post towns and postcode districts do not follow political boundaries and usually serve much larger areas than the place names with which they are associated. For example, within the PA postcode area the PA1 and PA78 postcode districts are 140 miles apart; and the eight postcode areas of the London post town cover only 40% of Greater London. The remainder of its area is covered by sections of twelve adjoining postcode areas: EN, IG, RM, DA, BR, TN, CR, SM, KT, TW, HA and UB.