Michael Bloch on the house that the future Edward VIII made the centre of high society in the Thirties
FORT BELVEDERE was built in the 1820s as a folly for royal tea parties: a battery of cannon was installed to be fired on royal birthdays by a resident bombardier. Diana Cooper wrote: "It was a child's idea of a fort. The sentries, one felt, must be of tin." The last "salute" was fired in 1907, and in 1910 the fort, on the south side of Windsor Great Park in Berkshire, near Ascot, became the "grace-and-favour residence" of a courtier. When it became vacant in 1929, the Prince of Wales asked to have it, and his father, King George V, granted it to him with the words: "What do you want that queer old place for? Those damn weekends I suppose!"

The Duke of Windsor wrote in his memoirs of the passion with which he rebuilt the fort and devoted himself to its hundred acres of garden. "I cleared away acres of dank laurel and replaced them with rare rhododendrons. I cut winding paths through fir and beech, revealing the true enchantment of the woodland setting ... I found a new contentment in working about the Fort with my own hands ... I pressed my weekend guests into arduous physical labour."

It was in these surroundings that he created a private life away from his official duties, and it was here that his friendship with Wallis Simpson (who visited for the first time with her husband in February 1932) developed.

When the Prince of Wales came to the throne in January 1936 as King Edward VIII, the fort assumed a special role as "the king's independent home" where he could escape from the tension and restrictions of court life. During the late autumn of that year, as the constitutional crisis arising out of his desire to marry Wallis developed, he withdrew to it in an atmosphere of virtual siege, and it was there that he signed the Instrument of Abdication on 10 December.

Before giving up the throne and leaving the country, however, Edward obtained an informal promise from his brother and successor, George VI, that he would be allowed to live at the fort when he returned to England. This promise was broken, as became clear during the Second World War when the Duke of Windsor learnt that, without his having been consulted, Fort Belvedere was to be made available for the evacuation of government offices.

He wrote bitterly to his London solicitor that this was "only another example of my brother's failure to keep his word to me of December 1936, when ... it was clearly understood verbally (unfortunately not in writing) that the Fort would be reserved for me until such time as it was mutually considered suitable that I should take up residence in England again ..."

After the war, the Windsors, who had decided to make their main home in France, asked on several occasions whether they might be allowed to live at the fort for a few weeks a year during the spring and autumn. As the duchess wrote to a friend in 1947: "We would not be there long enough to upset the powers that be ... It is a waste of time being homeless on the face of the earth and most disturbing..." However, these requests were always refused by the British royal establishment. In 1955, it was announced that the fort (which had been empty since 1936) would cease to be a grace-and-favour residence and would be let on a 99-year lease.

The first commercial tenant was the Duke of Windsor's nephew Gerald Lascelles. He refurbished it in a way that left few traces of its former occupancy. However, in 1977, Lascelles' successor as tenant, a son of the Emir of Dubai, sublet the fort to a television company for the making of the drama series Edward & Mrs Simpson, and thus it was briefly restored by expert hands to something of its former state. Fort Belvedere's present tenant is Galen Weston, the owner of Fortnum and Mason.

Michael Bloch is the editor of "The Intimate Correspondence of the Duke and Duchess of Windsor" (1986)