An extremely rare Queen Anne "Vigo" five guinea coin, discovered by a widow among her late husband's clothes, has sold for £296,160 ($474,915) as part of a UK auction.

The dies were made by chief engraver Henry Harris and his assistant John Croker

Following an intense bidding war between two collectors, the coin made a 146.8% increase on its £120,000 valuation. The unnamed woman had no idea that her husband was in possession of such a rare piece, which has been described as one of the most valuable and exotic of all British coins.

With Queen Anne having just taken the throne, the coin was minted from the gold seized from Spanish galleons at the Battle of Vigo Bay in October 1702. The British fleet was returning from an unsuccessful attempt at capturing Cadiz, when it discovered and destroyed the Franco-Spanish bullion fleet sheltering in Vigo Bay.

To cover for the failed attempt on Cadiz, the Vigo Bay victory was highly celebrated, distracting the attention of the public. Just 7lb 8oz of gold was recovered, and was received in person by master of the mint, Sir Isaac Newton.

Isaac Newton was instrumental in the Great Recoinage of 1696

It is believed that only a tiny number of five guinea coins were struck. The high value of the piece meant that they were only available to the wealthy, and therefore very few would have been purchased.

Today, less than 15 are held in private collections, with only six examples offered in the past 50 years. The example at auction was sold in very fine condition.

Paul Fraser Collectibles has an outstanding array of rare British coins for sale, including an exceptionally rare Charles I lightweight gold Unite, which was minted for only seven weeks in 1626.