The manor of Great Stanmore was owned by St Alban's Abbey at the time of the Norman Conquest. The manor was initially known as Stanmore-the first recorded division of Stanmore into "Great" and "Little" is in the Domesday Book. The Abbey leased the manor to various tenants until 1279 when Robert of Stanmore successfully claimed it. In 1362 it was acquired by the prior of St Bartholomew's, Smithfield, who already held the manor of Little Stanmore. The chief steward of St Bartholomew's, Geoffrey Chamber, leased the manor. He sold some of the property to Sir Pedro de Gamboa, a Spanish mercenary working for the royals. Chamber died in 1544, in heavy debt, and his estates were forfeited and granted to de Gamboa. However, he was murdered in 1550 and the manor was leased to Sir George Blage.
In 1604 the lordship was sold to Sir Thomas Lake, a secretary of state, and the owner of Little Stanmore. A fee farm rent was paid to the Crown, later granted to the chapter of Westminster. Later branches of the Lake family underwent much litigation relating to the ownership of the manor, and it subsequently went through several changes of owner and was subdivided. In 1715 the manor was once again united with Little Stanmore manor, this time under the Brydges family, earls of Carnarvon and dukes of Chandos. The manor was sold to James Hamilton, marquess (later duke) of Abercorn, and the owner of Bentley Priory. It was sold on to John Kelk, then in 1882 sold to Thomas Clutterbuck. The Clutterbuck family held the manor until 1936 when the manorial rights were extinguished.
Information from: 'Great Stanmore: Manor and other estates', A History of the County of Middlesex: Volume 5: Hendon, Kingsbury, Great Stanmore, Little Stanmore, Edmonton Enfield, Monken Hadley, South Mimms, Tottenham (1976), pp. 96-99 (available online).
The Manor of Little Stanmore was also known as Canons. In 1086 the manor belonged to Roger de Rames and remained in his family, although gifts of land were made to St Bartholomew the Great, West Smithfield, and to other churches; while parcels of land were sold, leased or transferred. By 1243 the Rames holding in Little Stanmore was divided between three tenants, leasing the land from St Bartholomew's. By 1353 the priory had increased its holdings to 957 and a half acres, the largest single estate of St Bartholomew's until the Dissolution. The priors leased out the manor house and gardens and portions of the estate, from 1501 referring to it as "Little Stanmore called Canons". St Bartholomew's surrendered to the Crown in 1539 and Little Stanmore was granted to Robert Fuller, the last prior. He died in 1540 and the manor reverted to the Crown, who granted it to Hugh Losse and his heirs.
In 1604 one of the Losse heirs sold the manor to Sir Thomas Lake. It remained in the Lake family until 1709 when it was sold to James Brydges, who became duke of Chandos in 1719. He rebuilt the mansion house of Canons in ostentatious style, including marbles, rare woods, ceiling paintings and tapestries. The grounds included canals, hothouses, an aviary and sculptures. His son Henry was forced by debts to break up the Canons estate, much of the furniture and collections of fine art were sold and the house was pulled down in 1753. The Brydges family (later the dukes of Buckingham and Chandos) retained the lordship of Little Stanmore and Great Stanmore, and kept a small amount of land in the area. William Hallett bought the Canons site and built a new, more modest villa. Canons then passed through various hands, with parcels of land sold off piecemeal, until 1929 when the mansion with 10 acres of land were bought by the North London Collegiate School, while part of the estate was purchased by Harrow Urban District Council to be used as a park.
Information from: 'Little Stanmore: Manors', A History of the County of Middlesex: Volume 5: Hendon, Kingsbury, Great Stanmore, Little Stanmore, Edmonton Enfield, Monken Hadley, South Mimms, Tottenham (1976), pp. 113-117 (available online).