A rare gold coin from the late 3rd century discovered by a very lucky metal detectorist will be going up for auction in London in June with an pre-sale estimate of £70,000-100,000. The 30-year-old finder was exploring a freshly-plowed field near Dover, Kent, when he found the coin. It was small, no bigger than a one-pence coin and weighed 4.31 grams (a teaspoon of butter weighs 5 grams). He thought it was a half sovereign at best, but when he sprayed away some of the soil, he saw the unmistakable shine of gold.

The finder figured it was probably fake, but had it examined by numismatic expert Dr Sam Moorhead at the British Museum. He identified it as an authentic Allectus aureus dating from 293-296 A.D., when the usurper emperor Allectus ruled in Britain. The British Museum has the only other exact match to it, discovered in Silchester, the city where Allectus died in battle against the forces of Emperor Constantius, in the 19th century.

On the obverse is a bust of Allectus facing right, bearing the laurel wreath. He wears a drape of fabric and a cuirass. It is inscribed IMP C ALLECTVS P F AVG (Commander Allectus, Dutiful and Fortunate Emperor). The reverse has an image of Sol wearing the radiate crown, his right arm raised and holding a globe in his left. He is flanked by two captives on their knees. The inscription reads ORIENS AVG (rising of the emperor). The reverse also bears the mintmark ML, the signature of the Londinium mint.

It is the second of its type found in Kent and is in excellent condition. Only a few small scrapes mar the original bright yellow gold surface.

Christopher Webb, Director and Head of the Coin Department at Dix Noonan Webb which will be auctioning the coin on June 12th:

“There are only twenty-four Aurei of Allectus known with nineteen different obverse dies recorded. This coin is a die match to one in the British Museum. Gold was initially produced to pay an accession donation in AD 293 but continued to be issued throughout his reign and were probably demonetized after his death in AD 296, as no coins of Carausius or Allectus are found in later hoards.”

Despite its extreme rarity, precious metal content and unquestionable museum quality (what with it being twinsies to the one in the British Museum), because it is only a single coin, it does not qualify as official treasure under the 1996 Treasure Act. The current definition of treasure requires two or more coins. The coroner’s inquest was not triggered and finders keepers is the only rule that applies. This is one of the loopholes of the Act like the one that let the Crosby Garrett Helmet fall into anonymous private hands.

Speaking of which, the UK’s Department for Digital, Culture, Media and Sport has announced planned revisions to the Treasure Act which would plug some of the holes. It would change the current sliding date standard (object 300 or more years old) to a fixed date of before 1714. Specifically addressing the Crosby Garret scenario, the proposed definition would cover anything that meets the age criterion with a value of over £10,000, regardless of material. Had the helmet been silver or gold, it would have been declared treasure; it was bronze. Any Roman object, even one of base metal and with less than £10,000 market value would also fall under the definition of treasure. The revisions would include single coins dated between 43 A.D. (the dawn of the Roman period), and 1344, the year that Edward III re-introduced gold coins to English currency.

The revised language is open to public consultation until April 30th. You can read the proposed revisions here (pdf), respond online here, or print a form and email/mail it to the Ministry.