Warren Davis, a spokesman for the National Trust, which owns 80 historic houses in Britain, said: 'In the 18th and 19th centuries, if you were a gentleman and had a means of introduction, you could visit houses when the family wasn't in residence. The royal palaces allowed the public in, so Buckingham Palace is reverting to what was a very long tradition in Tudor and Elizabethan England.'
Castle Howard, for example, which now attracts more than 200,000 visitors a year, has welcomed the public since it was completed in 1750. Chatsworth House and Blenheim Palace have done likewise.
But by 1928, the architect Clough William-Ellis had announced the death of the country house. 'It is a fact, patent to all and deplored by some, that the large-scale private paradise is already obsolescent,' he wrote in England and the Octopus. He blamed crippling taxation, poor estate management and a change in the social order, and appealed for action to save the nation's common heritage.
Groups like the National Trust and the Historic Houses Association, which represents 300 of Britain's historic houses, including Castle Howard and Blenheim, stepped in. By the 1960s, there was a surge in house openings, including Longleat, Woburn Abbey and Beaulieu. The chief motive was to finance maintenance.
Last year, the number of people visiting the association's homes fell by 3.6 per cent to 11 million. The revenue from public admission remains important, but is no longer enough to keep many houses open.