EPPING, England, Nov. 15, 2016 /PRNewswire/ -- Bonington's auction house near London will auction one of Britain's rarest coins on Wednesday, November 16. The company is offering to bidders worldwide a coveted Queen Anne "Vigo" 5-guinea gold coin valued at $240,000-$300,000. Photo - http://photos.prnewswire.com/prnh/20161114/439218 Photo - http://photos.prnewswire.com/prnh/20161114/439219 The coin is one of only 20 that were made from the 7.5lbs of gold the British seized from Spanish treasure ships in Vigo Bay, northern Spain, on Oct. 23, 1702 - exactly 314 years ago. It is one of only 15 known to have survived and is only the sixth example of its type to be offered for sale in the last 50 years. Remarkably, the coin had been kept in a little boy's treasure box after having passed down through four generations of the same family. No one in the family had the slightest inkling of its true value. "The coin was consigned to us by a gentleman from Hertfordshire whose grandfather had given it to him many years ago when he was a young boy. However, he had no idea what it was worth until recently, when he showed it to our coin specialist, Gregory Tong," said Boningtons spokesman Luke Bodalbhai. "Gregory immediately recognized the coin and informed the consignor of its value." Stunned and delighted by the news, the consignor related the coin's history. "My granddad travelled all over the world during his working life and collected many coins from the various countries where he had been," the consignor said. "As a boy, I was into pirate treasure, so he gave me bags of coins to play with. As time passed, these coins went back into bags and boxes and were forgotten about. Then, after my granddad passed away, I rediscovered the coins and recalled how much I had enjoyed them as a boy. So I gave them to my own son to play with, including the Queen Anne Vigo 5-guinea. He kept it in his treasure box and has been playing 'pirate' with it just as I did, all those years ago."