Each coin would have had a face value of £10, which would have been enough to buy a horse at the time, but are now worth more than £2,000 each, experts have said.
It is thought the coins were buried by a soldier loyal to King Charles at their camp in Wiltshire, the day before facing Parliamentary forces eight miles away at the Battle of Lansdowne.
Nigel Mills, consultant in coins and artefacts at Noonans auctioneers in Mayfair, central London, said: “We can imagine that on July 4, 1643, at a Royalist encampment near Box in Wiltshire, an army officer knelt and started digging in the dirt.
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