The constituency was created in its present form in 1974. It is home to the 474 acres of Mitcham Common, as well as the National Trustís Morden Park. It boasts the oldest cricket green in the world, and also marks the southern end of the Northern tube line.
It is a suburban seat where half the population regard themselves as Londoners and the other half still think that they live in Surrey. Labourís greatest strength has been found in the west and south of the seat and Tory support has tended to increase towards the east which borders Wimbledon.
Labour won the seat in 1974, and narrowly survived here in 1979. The then sitting MP, Bruce Douglas Mann joined the SDP. He was the only defector to seek a new mandate by causing a by-election, which was held in 1982 during the Falklands campaign. The Conservatives won and kept the seat, with diminishing majorities until 1997.