Various.

The manor of Isleworth or Isleworth Syon seems to have included land in Heston, Isleworth and Twickenham. In 1086 it belonged to Walter of Saint Valery, one of William the Conqueror's companions. The land subsequently passed into royal possession and was granted to Queen Isabel in 1327 and Queen Philippa in 1330. In 1421 the king granted Isleworth to the newly created abbey of Syon, in whose possession it remained until 1539. The Abbey was suppressed in 1539 and in 1547 the Duke of Somerset secured a grant of the estate to himself, which he held until his execution in 1552, although his widow continued to live at the manor until ordered to leave in 1554. The Crown leased the lands to various tenants until 1598 when Henry Percy, Earl of Northumberland, secured the tenancy rights. In 1604 he received a grant in fee of the house and manor with the park. The property descended to his heirs including Charles, Duke of Somerset (died 1748) and his son the Earl of Northumberland. Their descendants still owned Syon in 1958.

One notable event in the later history of the manor occurred in 1656. In that year articles of agreement were drawn up between Algernon, Earl of Northumberland, lord of the manor of Isleworth Syon, and Sir Thomas Ingram and other principal copyhold tenants. These articles established certain of the customs of the manor on a firm basis. Fines and heriots were to be certain and not arbitrary, at the will of the lord. The tenure of customary and was to be by Borough English, whereby the youngest son of a copy holder inherited on the death of his father. These articles were signed on 20 May 1656 and were confirmed by a decree in Chancery, 28 June 1656 (see ACC/1379/330 and partial transcript in History of Syon and Isleworth by G. Aungier, p.206). A printed tract called Isleworth Syon's Peace was to be published in 1657 and according to Aungier was to be placed in the Isleworth parish chest. London Metropolitan Archives possesses copies in ACC/0479 and ACC/1379.