HS2 unearths Iron Age coin hoard in Hillingdon

'It takes us back to the tumultuous time of Julius Caesar’s conquest of Gaul.'

A large Iron Age coin hoard has been uncovered near Hillingdon in West London during excavations in advance of the HS2 project.

Over 300 Iron Age potins were discovered during HS2’s archaeology work in Hillingdon. Image: HS2.

The discovery was made last August and has just been announced. Just as archaeological work was concluding on the site, the team found a large dark green/blue patch of soil, which often indicates the presence of oxidised metal, and they quickly began to reveal a loosely packed group of metal discs. With no other significant Iron Age artefacts or features recovered in the vicinity, the team believes that this was perhaps an isolated location at the time of the hoard’s burial.

Once removed from the ground, the coins were taken to the Birmingham Museum and Art Gallery where they were cleaned and conserved. This post-excavation analysis found that the hoard consists of over 300 potins – a type of Iron Age coin usually made out of an alloy of copper, tin, and lead.

Hillingdon hoard in-situ. Image: HS2.

Potins are believed to have first been struck near Marseille, France, over 2,000 years ago, and feature a left-facing head of Apollo on one side and a bull charging to the right on the other. Their use quickly spread across northern Europe and it is thought that the first series of potins to be produced in Britain were the Kentish Primary or Thurrock types, which were probably made no later than 150 BC. Over the next couple of decades these once bulky coins became thinner and the bull and Apollo head began to become more stylised – becoming known as Flat Linear types. The coins from the Hillingdon hoard are believed to be from late in this Flat Linear sequence.

While the hoard is similar in size to the Sunbury hoard, which was discovered in 2010, also in West London, potins from the Hillingdon hoard are believed to be later in date, making it the first sizeable hoard of potins from this period to be discovered in Britain.

A potin from the HIllingdon Hoard cleaned and showing a stylised bull. Image: HS2.

Commenting on the discovery, Duncan Wilson, the chief executive of Historic England, said: ‘They say that money talks, so what can this unexpected discovery tell us? 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. Hoards like this are now protected by law so that they can be studied to learn more about how these early coins were used, and perhaps shed light on why they came to be hidden in a seemingly remote place.’

The potins bear the left-facing head of Apollo on one side and a bull charging right on the other. Image: HS2.

As required by the new definition of Treasure, the hoard is now being examined by a coroner who will determine its value. As HS2 will not make any claim on it, it is expected that it will be acquired by a museum once evaluations are concluded.