Blackfen is an area of South East London, England, within the London Borough of Bexley. It is located north of Sidcup and south of Welling. Prior to the creation of Greater London in 1965 it was in 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.