The vendor had been given the coins by his grandfather shortly after their discovery in the 1970s and had kept them in a shoebox until they came to light at a valuation day four years ago.
A total of 59 coins, probably hidden at the beginning of the English Civil War when they had a face value of £59, were discovered when builders were digging footings for a building in the Chipping Norton area. The ground collapsed revealing a hidden cellar which was subsequently demolished. The coins were found in a space behind a large stone in the cellar wall.
With no idea of their significance, the builder who found them gave the coins to his ten-year-old grandson, who was already an avid collector of stamps, marbles and seashells.
They ended up in his shoebox of childhood treasures and remained there until 2005 when - with the costs of a wedding to meet - they were taken to a valuation day run by Morton & Eden in association with Sotheby's in Cheltenham. Specialist James Morton identified them and subsequently reported to the British Museum as potential Treasure Trove.
"We took them along hoping they might pay for a honeymoon in Spain," said the owner of the coins. "When we learned they were gold and worth so much, we thought about Mexico."
However, the Coroner's inquest process required in such Treasure Trove cases proved lengthy and, four years later, the 39-year-old vendor is married with two children. The consolation is that values of gold coinage have risen appreciably in the interim.
The British Museum negotiated the purchase of two of the coins for the National Collection while the remaining 57 were released to the owner by a Coroner's Court and will be auctioned in a sale on June 9-10.
This particular hoard of unites - so called because the inscription to the reverse refers to the union between England and Scotland under James I - are interesting social documents.
"The remarkable thing about this collection is that each coin is different," said James Morton. "Each has different mint marks and styles and five of the coins were originally minted in Scotland for circulation there. There is some suggestion that James I coinage was preferred over that of Charles I. It was made of 22 carat 'crown gold' standard and, clearly, whoever hid these coins for safekeeping deliberately chose them as the most reliable store of wealth.
The coins will be sold individually with estimates, dependent on condition and rarity, ranging from £400 to £2500.
• The British Museum have issued an appeal for funds to purchase the so-called Vale of York hoard found in 2007 in a field near Harrogate.
The early tenth century hoard consists of some 617 coins, a magnificent Viking silver bowl and associated artefacts and jewellery of the Viking period.
The coins - English, Anglo-Viking, Carolingian and a few Islamic examples from as far away as Afghanistan - include unique and rare types. They were scientifically excavated, thanks to the understanding of the metal detectorists involved.
It is considered the most spectacular and internationally significant Viking hoard for 150 years - the last comparable hoard was found at Cuerdale in Lancashire in May 1840. Much of this is in the British Museum already.
The museum have just four months to raise £1,082,800 and say at least £250,000 is urgently required. Every individual donation, which can be gift-aided, will be matched on a pound-for-pound basis. Contact 0207 323 8195.
By Roland Arkell