Unknown

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.