 Ruislip formed an ancient parish of 6 @,@ 585 acres ( 26 @.@ 65 km2 ) in the Elthorne hundred of Middlesex . Following the Poor Law Amendment Act 1834 , the parish lost control of poor relief to Uxbridge Poor Law Union and it was grouped into the Uxbridge rural sanitary district in 1875 . In 1894 the sanitary district was replaced by Uxbridge Rural District and the parish vestry was replaced with a parish council . Due to increasing population , the parish split off from the rural district and formed the Ruislip @-@ Northwood Urban District , with the parish council replaced by an urban district council . The urban district was abolished in 1965 and was transferred to Greater London to form part of the newly established London Borough of Hillingdon . 
