A 16th-century gold portrait medal of Queen Mary I was sold for a record £276,000, according to an auctioneer.
London-based Morton & Eden said the lot became the "most expensive historical medal" to go under the hammer.
The sale price topped the previous high of £243,200 set by the same medal when it was last auctioned in 2005, a spokesman for the auctioneer said.
The medal was made in 1554 - the year of Mary's marriage to the future Philip II of Spain - and was once owned by the late Baroness Rothschild, a member of the Rothschild banking family.
New York dealer and collector Lawrence R. Stack was in the sale room to see his collection of Renaissance medals fetch a total of £1.8 million.
Queen Mary I earned the nickname "Bloody Mary" after ordering hundreds of religious dissenters to be burned at the stake.