Another Out-of-Place Artefact in a British Field

Metal detectorist John Stoner, 42, has dug up an extremely rare New England coin in a field outside the village of King's Clipstone in Nottinghamshire (Paul Harris, 'Minted! Dug up in a Midlands field, a £1m 'perfect' US threepenny bit from the time of the Pilgrim Fathers' Daily Mail, 6 September 2014). It was a 1652 silver threepenny coin, "an uneven, hand-hammered coin, about the size of a modern 1p but thinner", from the first authorised colonial coinage, commissioned and struck in Boston, Massachusetts. It is expected to sell for up to £1million when it is auctioned by St James’s Auctions in London on December 2nd. Because it is a single coin, it is not subject to the Treasure laws.

It has been hailed as one of the finest examples of a currency produced in the days of the Pilgrim Fathers in a land that would become the United States. [...] Mr Stoner, who temporarily mislaid the coin at one point, found it while on an outing with the Coil To The Soil metal detector club on Sunday.  

 Look at the timing, according to the journalist, Sunday 31st August it was found. By the 6th September, it had been shown to several auction houses, one of them agreed to sell it, arrangements were made to send it to the US for "expert cleaning" there, and it was already on the way when the article went to press. "Not in it fer the munny" they all say, yet when needs be, many of them apparently have lots of contacts so they and the compliant landowner can cash in quickly on the hobby.

So, how and when did this coin, not legal currency in the British Isles, actually reach a Nottinghamshire field? Was it brought back by a 17th century sailor intending to use it in a Boston whorehouse on his next voyage, or was it lost by a modern collector? Or is there some other explanation? This coin seems not to be one of the seven in the PAS database.