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

Expected to fetch between £2-3 million, it was sold for just over £4 million, once the buyer’s premium to Sotheby’s had been added. It was the most anyone has paid for a Romney painting.

Most of the portraits were collected in the late 18th century by the 2nd Earl of Warwick, an art collector whose obsession left him penniless by his death in 1816.

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.