Historic Houses Association

Historic Houses (formerly, and still for legal purposes, known as the Historic Houses Association or HHA) is a not-for-profit organisation that represents well over a thousand independently owned historic country houses, castles and gardens throughout the United Kingdom. == History == The association originated as the Historic Houses Committee of the British Tourist Authority, and was independently established in 1973 to help owners maintain and conserve significant homes in the interests of the nation's heritage.

Source: Wikipedia — Historic Houses Association (CC BY-SA 4.0)