A NEWLY discovered letter written by the novelist Evelyn Waugh shortly before his wife ran off with another man is to be auctioned.

Waugh, the author of Brideshead Revisited and Decline and Fall, was educated at Lancing College in Sussex between 1917 and 1921 and was married to Evelyn Gardner in 1928.

The letter was written in 1929 on the paper of an Istanbul hotel where he and his wife Evelyn were staying during a cruise that doubled as a delayed honeymoon and a working trip for Waugh, who had been commissioned to write a travel book.

Already halfway through his acclaimed novel Vile Bodies, Waugh wrote a reply to a party invitation from an old university friend, Eleanor Watts, explaining he could not attend because he was “chained hand and foot to this novel I am writing”.

A few days after the Waughs returned to London, his wife ran off with Eleanor's boyfriend, BBC assistant producer John Heygate.

Their subsequent divorce was “pivotal” in Waugh’s life, according to Matthew Haley, the Head of Books at auctioneers Bonhams.

“The experience contributed to turning him from a good novelist to a great one,” he added.

The letter will be auctioned by Bonhams in London on June 18 and is estimated to fetch between £1,000 and £1,500.