In spring 1956, Deborah, Duchess of Devonshire - youngest of the six legendary Mitford sisters - invited the writer and war hero Patrick Leigh Fermor to visit Lismore Castle, the Devonshires’ house in Ireland. This halcyon visit sparked off a deep friendship and a lifelong exchange of sporadic but highly entertaining letters.

There can rarely have been such contrasting styles: Debo, unashamed philistine and self-professed illiterate (though suspected by her friends of being a secret reader), darts from subject to subject while Paddy, polyglot, widely read prose virtuoso, replies in the fluent, polished manner that has earned him recognition as one of the finest writers in the English language.

Prose notwithstanding, the two friends have much in common: a huge enjoyment of life, youthful high spirits, warmth, generosity and lack of malice. There are glimpses of President Kennedy’s inauguration, weekends at Sandringham, stag hunting in France, filming with Errol Flynn in French Equatorial Africa and, above all, of life at Chatsworth, the great house that Debo spent much of her life restoring, and of Paddy in the house that he and his wife Joan designed and built on the southernmost peninsula of Greece.