We tend to view the English country house through the Merchant & Ivory lens. But from the late Middle Ages up to the Second World War, country houses were Britain’s greatest contribution to art and architecture. Almost all her great architects—Inigo Jones, Christopher Wren, Vanbrugh, Hawksmoor, William Kent, the Adams, Nash, Sir John Soane, Barry, even the arch-Gothick Pugin, up through Norman Shaw, Voysey, and Lutyens—not to mention dozens of unknowns—made their mark on these houses. Country houses were a focal point for the patronage and the collecting of art as well. The gentleman’s “cabinet of curiosities” and the paintings he hung in his drawing room were the first British museums and galleries. When I look at Velázquez’s Rokeby Venus in the National Gallery, I often think of its nineteenth-century owner, J. B. S. Morritt, who called the painting “my fine picture of Venus’s backside which I have at length exalted over my chimney piece in the library.” The end of a half-millennium of aristocratic civilization that the destruction of the country house marks is, along with tragedy of the Great War and Britain’s stubborn refusal to surrender to tyranny during World War II, one of the great stories of the last century.

Britain’s National Trust was founded in the hope of preserving as many of the nation’s most distinctive great houses as possible. In the Trust’s early years the young James Lees-Milne went to work there and was given