Brownsea Island by third parties, is owned by the National Trust. Most of the buildings are situated near the small landing stage. The northern portion of the island is a Nature Reserve managed by Dorset Wildlife Trust and an important habitat for birds; this part of the island has limited public access. A small portion to the southeast of the island, along with Brownsea Castle, is leased to the John Lewis Partnership for use as a holiday hotel for staff, and is not open to the public. The island forms part of the Studland civil parish in the Purbeck local government district.
Brownsea Island instigator of Pride's Purge– the only military coup d'état in English history – was stationed on the island in 1654. Sir Robert Clayton, a Lord Mayor of the City of London and wealthy merchant became owner in the mid-1650s and after his death in 1707 the island was sold to William Benson, a Whig Member of Parliament and architect. He converted the castle into a residence and was responsible for introducing many varieties of trees to the island. In 1765 Sir Humphrey Sturt, a local landowner and MP purchased the island, which in turn passed to his sons. Sturt expanded