They include English Heritage chair Baroness Andrews, the Marquess of Cholmondeley, owner of Houghton Hall in Norfolk, and Historic Houses Association (HHA) president and owner of the Brampton Bryan estate Edward Harley.
The event will take place at the Queen Elizabeth II Conference Centre in central on 16 November from 9am to 5pm.
Lord Cholmondeley will give the HHA/Smiths Gore Lecture, in which he will speak about the programme of work he has carried out at Houghton Hall and the creation of a walled garden in memory of his grandmother.
Baroness Andrews is former parks minister as parliamentary under secretary of state for communities and local government. She became English Heritage chair in July 2009.
Delegates are either owners of historic buildings or involved in the upkeep, restoration or conservation of historic buildings, their contents or associated landscapes. The event also features 70 exhibitors and expects 1,000 guests.
The HHA has 1,500 member houses consisting of listed buildings or designated gardens, usually grade I or II*. Around 500 HHA houses and gardens are open to the public, attracting 15 million visitors each year.
- To register, see www.hall-mccartney.co.uk/HBPGEform.htm or call 01462 896688.