Isleworth, a settlement located in Middlesex, was already an established farming and trading community of high value prior to the Norman Conquest in 1066. The settlement was situated from the Middlesex bank of the River Thames towards the centre of Hounslow, including the land of later Hounslow Priory, and extended to the borders of Southall in Hayes parish. The Domesday Book of 1086 recorded Isleworth, known as Gistelesworde, with 55 ploughlands, 118 households, and an annual amount rendered of £72 to its feudal system overlords.

Following the Conquest, the manor of Isleworth was held by successive Norman barons of the St Valeri family, although there is no evidence that they ever resided there. The manor was instead held as a source of revenue and power. One of the later barons granted several manorial rents and privileges to London’s Hospital of St Giles. He also gave the church and advowson to the Abbey of St Valeri, which was situated at the mouth of the Somme in Picardy.