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HS2 Excavation Hillingdon Hoard of Potins a “Once-In-A-Lifetime Find”

HS2 Excavation Hillingdon Hoard of Potins a “Once-In-A-Lifetime Find”

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While searching for artifacts in a secluded spot in the West London borough of Hillingdon in August 2020, a team of archaeologists assigned to the HS2 high-speed rail project hit the jackpot, both figuratively and literally in archaeological terms. The Hillingdon Hoard is a “once-in-a-lifetime find” and one of the most important collections of Iron Age coins discovered on British soil to date.

The Hillingdon Hoard was discovered after a storm partially uncovered the ancient collection of potins. (HS2)

The Hillingdon Hoard was discovered after a storm partially uncovered the ancient collection of potins. (HS2)

Finding Rare Potins in the Dirt: Unearthing the Hillingdon Hoard

According to the HS2 website, the High Speed 2 (HS2) project is the development of a “new high speed railway linking up London, the Midlands, the North and Scotland” which is set to connect “around 30 million people.” In advance of the work, set to take place over several phases until completion in 2035, the organization is conducting exploratory excavations.

During excavations, they spotted a collection of round objects lying loose on the ground. Although the small objects were caked with dirt, they still shone through enough to be identified as something metal. After a closer examination, the archaeologists realized they were looking at coins of a highly unusual type.

The imagery inscribed on the coins revealed that they were an especially ancient coin, of a kind that had been manufactured in Britain way back in the 1st and 2nd centuries BC. These types of coins are known as potins, a term which refers to the metal alloy that was used to make them, a copper/tin/lead alloy that has a silverish appearance.

The potins, or coins, which made up the so-called Hillingdon Hoard, were found caked in dirt. (HS2)

The potins, or coins, which made up the so-called Hillingdon Hoard, were found caked in dirt. (HS2)

Discovery of Hillingdon Hoard During Rail Project Excavations

HS2’s archaeological excavations are being carried out by the project’s enabling works contractor, Costain Skanska Joint Venture. Their latest discovery in Hillingdon was made possible by a storm that washed away the layer of soil that had kept the hoard of Iron Age coins hidden for so long.

“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 color from what it would be expected to be,” explained Emma Tetlow, the Costain Skanska supervisor leading the exploration project, in an HS2 press release. “The patch of soil was dark greeny-blue which suggests oxidized metal, and when we checked more closely, we could see loosely packed metal discs.”

In all, the archaeologists recovered more than 300 of these Iron Age-minted coins. A more detailed analysis revealed that the coins had been manufactured sometime in the 1st century BC. This doesn’t necessarily mean the hoard was buried at that time, since the coins were durable and could have remained in circulation for many decades after they were originally made. This “once in a lifetime find,” Tetlow continued, “allows us to expand our knowledge of what life could have been like in Hillingdon many centuries ago.”

The so-called Hillingdon Hoard is one of the most significant collections of ancient Iron Age coins ever found on British soil. Another collection found in 2010 (the Sudbury Hoard) was similar in size, but was comprised of coins that had been made at an earlier date. Previously, only a few coins from the later time period had been found, which is why the Hillingdon Hoard is so special.

A History of Potins and the Mareselle Coin

Sometime in the 2nd century BC in the Mediterranean coastal city of Marseille, France, coin-makers created the first potin-style coins. They were inscribed with the image of the Greek and Roman god Apollo on one side, and with a picture of a charging bull on the other.

Marseille was founded as a Greek colony in approximately 600 BC, and its cultural history was reflected in it choice of coin iconography. Apollo was a god who represented knowledge and enlightenment, among many other virtues. The bull was also an image featured frequently in Greek mythology, having been inherited from the highly influential Greek Minoan culture that had thrived on the island of Crete in the 2nd and 3rd millennia BC.

Being manufactured in one of the most important seaports in the Mediterranean, the Marseille coins were easily distributed and proved to be popular on trade routes that reached into Northern Europe. Soon other city-states and nations, including Britain, began making their own coins, largely mimicking the designs of the Marseille originals.

The Hillingdon Hoard potins depict Apollo on one side and a bull charging on the other. (HS2)

Potins Cross Over into Britain: Origins of the Hillingdon Hoard Coins

The first potins made in Britain are known as Kentish Primary or Thurrock types, and were in circulation by at least 150 BC. They were relatively heavy and bulky, and by 100 BC they had been replaced by more streamlined designs known as Flat Linear.

The Flat Linear style produced a number of varieties of coin, which were put into circulation in sequence over the remaining decades of the 1st century BC. The depictions of Apollo and the bull became more abstract and stylized over time, and those changes have helped archaeologists determine when coins found during excavations were manufactured.

The potins from the Hillingdon Hoard contained images that were highly stylized. This means they were made at a later point in the Flat Linear production sequence, presumably sometime in the latter stages of the first century BC. These particular coins were manufactured at a time of great uncertainty in Britain. Celtic tribes controlled most regions of the country, but the Romans were looming just over the horizon.

The forces of the Roman Republic under Julius Caesar invaded Britain in 58 BC. While this initial excursion was successfully repelled, everyone knew the Romans would return eventually—which they did, in 43 AD, launching a war of conquest ordered by Roman Emperor Claudius that was destined to succeed.

One of the potins, before and after cleaning. (HS2)

HS2 Excavations Deepening Knowledge of Lost British Cultures

Archaeologists and historians are excited by the discovery of the Hillingdon Hoard. But at present they remain unsure as to why the coins were collected and hidden in the earth. The hoard location was far away from any large settlement (the ancient version of London was only founded after the Roman conquest).

Some believe the hoard may have been buried as a way to establish a property line, thereby proving ownership of a particular piece of land. Others think the coins may have been left as a sacrifice to the Gods, given the fact they were buried in a remote area near what may have been considered a sacred spring and woodland area.

Another possibility is that the hoard was hidden to prevent its being stolen, to be retrieved later when it was really needed. If the coins had been in circulation for a long time, the cache may have been buried in response to the Roman invasion of the first century AD, which would have created a high level of fear and uncertainty among the population. A wealthy coin collector might have been worried that an invading army would seize his most prized possession.

Whatever the motivations of the person or persons who buried it, this substantial collection of ancient coins is a remarkable find. It is just one of many such discoveries that have been credited to HS2 archaeological excavations, which has helped expand knowledge about the cultures of several different eras of British history.

“At HS2 we are not only building for the future, we are also preserving the past,” said HS2 Helen Wass, commenting on this latest discovery. “This is an exciting find for our team of archaeologists and provides us with more information about how our ancestors lived and settled in London. HS2’s unprecedented archaeological program has enabled us to tell the stories of our history and leave a lasting legacy for future generations.”

Top image: The Hillingdon Hoard, a collection of coins of potins, took its name from the location where it was discovered in London. Source: HS2

By Nathan Falde



Crasslee's picture

Thanks for a nice little overview on the discovery of the Hillingdon Hoard. Just one thing doesn't make sense, and isn't explained in your piece. Why do you on two separate occasions refer to the Hillingdon Hoard as 'the so called Hillingdon Hoard'? In the UK discovering any grouping of more than three coins over three hundred years of age are classed as a hoard. In which case I don't understand why the 'so called' prefix was used?


A breathtaking find.  Just think of what else might be buried.

Nathan Falde's picture


Nathan Falde graduated from American Public University in 2010 with a Bachelors Degree in History, and has a long-standing fascination with ancient history, historical mysteries, mythology, astronomy and esoteric topics of all types. He is a full-time freelance writer from... Read More

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