I dug up a 650-year-old silver coin in my backyard

Stumbling upon hidden treasure has an ageless appeal, from Robert Louis Stephenson’s classic 1883 novel Treasure Island to TV show The Detectorists.

Recently I found some buried treasure of my own, in the form of an old silver coin. 

The most valuable thing about it turned out to be its history, rather than it being worth huge amounts of money.

But I think the story of this one little coin teaches us modern-day lessons about the value of money, and how the way we make and spend coins has barely changed in 650 years.

It even tells us something about the ever-present nature of fraud.

Recently I was digging up some weeds in my garden that were threatening to overrun my vegetable patch, when I saw something glinting in some overturned earth.

Thinking it was an old bottle cap, I went to pick it up – only to find it was a silver coin. Brushing the soil away, I was intrigued to find that the coin looked old, and was covered in Latin writing as well as the image of a king that I did not recognise.

Taking my find inside, I decided to learn as much as I could about the coin – with my immediate thought being that it could be valuable, and that I might even find more buried in the earth.

So I spoke to some coin experts to find out more about the history of this mysterious coin with, I think, some fascinating results.

A numismatic expert at Hattons of London – the technical term for someone who studies money and coins – informed me that the coin is a silver groat, made in the reign of King Edward III between 1356 and 1361 and made of 92.5 per cent pure silver.

My daydreams of selling the coin and taking early retirement were about to be squashed, however, as Hattons then valued it at around £100 to £150, while auctioneers Warwick & Warwick valued it at £50 to £80.

Barely enough to call yourself rich by the standards of 1361, let alone 2024.

The groat was worth 4p back in the 14th century, which was about two day’s wages for a basic labourer, or one day’s wage for a skilled worker such as a carpenter.

The coin would have bought two chickens, 16 pints of beer, 2lb of cheese or two dozen eggs in medieval times.

Sadly my Latin is a bit rusty, and I could not decipher the fragmented text printed onto the coin – bar the word ‘London’ and ‘Edward’.

Fortunately, Hattons could.

The ‘heads’ side of the coin reads ‘Edward DG Rex ANGL & Franc D Hyb’ – or ‘Edward, by the Grace of God, king of England and France, Lord of Ireland’.

On the opposite side, the Latin ‘Posui Deum A Diutor Em Meu’ translates as ‘I have made God my helper’, and the text ‘Civi Tas London’ means, as you can probably guess, that the coin was minted in London – in the Tower of London, to be precise.

In a way, very little has changed when it comes to the monarch’s impact on our money today.

Not only do coins still feature the likeness of the ruling king or queen, but many still bear text implying they have a divine right to rule, despite our increasingly secular culture.

For example, take the inscription found on today’s £1 coins – ‘Charles III Dei Gra Rex Fid Def’, or ‘King Charles III, reigning by the grace of God, defender of the faith’.

The coin itself also features an interesting early anti-fraud feature.

The ‘tails’ side of the coin has a large cross, which goes from edge to edge. The point of this cross is to make it obvious if someone had removed metal from the edge, known as ‘clipping’.

If a criminal clipped enough coins, they could essentially make free money by melting the silver filings down and making new fake currency, or else make silver bullion to sell on.

So in 1247, mints began making coins with the so-called ‘long cross’ design, which would make clipped coins easier to spot.

This mattered in the middle ages, as the value of a coin was based on the value of the precious metal within it, and public trust in that notion underpinned the whole idea of coinage.

‘This was an era when the money in your pocket was worth only as much as the precious metal they contained,’ Hattons said.

Merchants took a dim view of clipped coins, which were essentially less valuable than intact ones, and coin clippers could face the death penalty if caught.

The silver groat I dug up appears to have escaped the coin clippers’ shears and is intact and in pretty decent condition – despite the best efforts of 14th-century fraudsters.

Again, not much has changed with physical money today when it comes to fighting fraud. We still build anti-crime measures into every coin and banknote, it is just that our methods have improved.

I’m not sure what a medieval coinsmith would have made of holographic banknotes, but they would have recognised that we shared the same goal of making currency harder to fake.

Could you find your own medieval coin? 

If you own a metal detector then you have a decent chance of finding such a coin yourself.

Richard Beale, collectibles department valuer at auctioneers Warwick & Warwick, said: ‘A lot of coins from this period and earlier are being discovered by detectorists, there has been a lot of publicity about valuable hoards of coins being discovered and this has encouraged landowners to allow detectorists onto their land.’

But if you are lucky enough to dig up treasure, you can’t just rely on the principle of ‘finders keepers’.

Buried coins can have an important cultural and financial value, and so you may need to register anything you find.

If you find treasure, you have to tell your local coroner’s office inside 14 days. The coroner will value it and attempt to sell it to a museum.

If you own the land the item was found on, you will be paid all of its value, and if you find it elsewhere then you will get up to 50 per cent. You will need landowners’ permission. You may have to pay capital gains tax.

Treasure is any metal object that is at least 300 years old and contains no less than 10 per cent precious metal.

If that object is a coin, you need to have found at least two for it to count as treasure. However, if you find coins with less than 10 per cent precious metal then they do not count as treasure unless you find 10 or more.

Prehistoric metal objects are always treasure, and if you find two prehistoric items in the same place they are treasure even if not made of metal.

If you find precious metal items less than 300 years old, you need to report them if they were hidden on purpose.

From 30 July, any item may be treasure if it is made of any metal, is at least 200 years old and is historically important.

Sadly, I never did uncover any more silver groats hidden among the weeds in my garden, and I clearly would need to find quite a few to die a rich man.

But this one little coin has still proved invaluable, teaching me more about the history of money, how little has changed – and, sadly, the never-ending efforts of ne’er-do-wells to part us from that money.

Kings and queens come and go, but fraudsters, it seems, are here to stay.