Blackfen is an area of south-east London, England, north of Sidcup in the London Borough of Bexley and not the historic county of Kent.
“Blackfen” means a black, marshy area. The soil is dark and fertile and the area around Blackfen Road and Wellington Avenue is prone to flooding in extreme conditions. The housing stock is almost exclusively owner-occupied houses of conventional British design. The sale of the Danson Estate in 1922 marked the beginning of a major period of house building in the area and most of the houses date from the 1930s.