AN EARL who sparked outrage when he banned gay weddings at his castle is selling off his ancestor's handwritten account of the dramas of the Civil War.

Lord Devon, who lost the wedding licence after he refused single-sex unions at Powderham Castle, near Exeter, hopes to raise up to £15,000 auctioning a book written by his ancestor Sir William Waller 300 years ago.

The family heirloom relates the colourful life of Sir William, who was commander-in-chief of Parliament forces in the Westcountry during the Civil War. His loyalty to Parliament against the Army saw him exiled, and later imprisoned when he returned.

While he was locked up, he penned the "highly wrought" prose, in which he sought to refute some of the accusations made against him.

The resulting book, the Vindication of the Character and Conduct of Sir William Waller, is one of two manuscripts he wrote. The tome, handwritten in a "single elegant italic hand", will go for auction at Sotheby's on July 14.

Sotheby's said the book, lot number 400 in the sale, described the "escalating tensions" between Parliament and the Army, leading to the seizure of the king, as well as dramatic accounts of Sir William's own experiences.

A spokesman for the auction house said: "In highly wrought rhetorical prose replete with citations from classical and biblical authorities, he refutes the various accusations made against him through a detailed account of his actions over the previous years, and also explains his own moderate political and religious position."

Sir William's daughter, Margaret Waller, married Sir William Courtenay, who lived at Powderham Castle – now one of the oldest family houses in England, built in 1390.

The book has been in the family of the Earl of Devon ever since.

In May, Lord Devon hit the headlines when he refused to allow civil partnerships at the castle because of his religious beliefs. Gay rights campaigners took up the issue and Devon County Council ruled that his stance was discrimination and revoked the licence.

At the time, Lord Devon said: "I have to follow my religion in this case. The question has never arisen here before, but I suppose I knew it always would at some time."

The earl claimed to have had 250 messages of support, but the couple who first complained about his refusal to let them marry at Powderham said they were "outraged" at his position.

At the time, Ben Summerskill, chief executive officer of the gay rights group Stonewall, said: "If you open up your premises to the public, it is to all the public."