Ashford is a town almost wholly in the Borough of Spelthorne, Surrey, with a small area contained within the boundaries of the London Borough of Hounslow, approximately 14 mi (23 km) west-southwest of central London. Its name derives from a crossing point of the River Ash, a distributary of the River Colne. Historically part of Middlesex, the town's wards have been part of Surrey County Council since 1965. Ashford consists of relatively low density low- and medium-rise buildings, none of them being high rise. If excluding apartments (at the last census 27% of the housing stock) most houses are semi-detached.