From the Wikipedia page on Sidcup [1]
Sidcup parish formed the Sidcup Urban District of Kent from 1908. It was initially known as Foots Cray; however, in 1921 the urban district, and in 1925 the parish, were renamed Sidcup. The parish and district were abolished in 1934 and combined with Chislehurst to form the Chislehurst and Sidcup civil parish and urban district. In 1965 the parish and urban district were abolished. Sidcup went on to form part of the London Borough of Bexley in Greater London and Chislehurst formed part of the London Borough of Bromley.