Archaeologists working on the HS2 route in Hillingdon, west London, have uncovered three hundred Iron Age coins. Described as a “once-in-a-lifetime find”, the coins were found after a storm disturbed the ground where they had been buried many centuries ago.

“We were coming to the end of our archaeological work on the site when we found a patch of soil that was a very different colour from what it would be expected to be,” recalled Emma Tetlow, Historic Environment Lead for HS2’s main contractor Skanska Costain and Strabag.

This is the largest archaeology programme ever undertaken in the UK, following the line of the new highspeed railway HS2. Head of Heritage at the project, Helen Wass, explained that “HS2’s unprecedented archaeological programme has enabled us to tell the stories of our history and leave a lasting legacy for future generations.”

Measuring around 3cm in diameter, the coins are known as ‘potins’. They circulated in Kent, Essex, Hertfordshire and Europe almost 2,170 years ago, just before the invasion of Britain by the Romans. The potins bear the Greek god Apollo in profile on one side and a charging bull on the other, which is based on the design of coins originally struck in Marseille, France.

 “They say that money talks, so what can this unexpected discovery tell us?” said Duncan Wilson, chief executive of Historic England. “It takes us back to the tumultuous time of Julius Caesar’s conquest of Gaul. Reaching Britain in 55 and 54 BC, he observed the locals using ‘bronze’ coins, an innovation they had adopted not long before through cross-channel migration and trade.”

Experts believe the hoard may have been buried to mark a property boundary, as an offering to the Gods, or to hide them from the Romans after they finally conquered England in AD 43. This type of small coin was relatively uncommon in his period, when bartering was often used to acquire desirable objects.

Birmingham Museum and Art Gallery have since cleaned and preserved the coins. A coroner will now determine whether the coin hoard amounts to ‘treasure’, after which they could be acquired by a museum.