They used to hang in Warwick Castle until they were removed when Lord Brooke, later the 8th Earl of Warwick, sold the castle to Maddam Tussauds for £1.5 million in 1978.

The paintings now belong to his son, who grew up in Warwick Castle and went to Eton College, and is now believed to be living in Bali, Indonesia, with his third wife and two youngest children.

The highlight of the auction is a portrait of Edward Wortley Montagu painted by George Romney in Venice in 1775.

Expected to fetch between £2-3 million, Sotheby’s expert Alex Bell described it as “a combination of an English grand manor style coupled with a Venetian portrait painting of the 16th century”.

A portrait of a bearded man by Jan Sanders Van Hemessen that had belonged to Prince William of Orange before it came into the 2nd Earl’s ownership is expected to go for between £800,000 and £1.2 million.

A portrait of John Wilmot, the 2nd Earl of Rochester, with a monkey, could fetch £600,000 and two other portraits have estimated price tags of £1/2 million.

It is unknown how many paintings are in the collection but if the sale of these five portraits alone reach their top estimates, the 9th Earl could be expecting around £5.8 million.

The 2nd Earl of Warwick, George Greville, was an art collector. Although he brought some of the greatest paintings into the collection at Warwick Castle during the late 18th century, his obsession left him penniless by his death in 1816.