Prof Ged Martin reveals his theory about the 448 historical coins dug up in 1938

It was an August day in 1938. Workmen were widening the road from Hornchurch to Upminster. Digging opposite St Andrew’s Church, they spotted silver coins glinting in the clay. Next day, more were found.

There were 448 of them, from the reign of King Henry III.

The coins came from the site of Hornchurch Priory. Unlike an inward-looking monastery with its abbot and monks, this was a community of canons (“brethren”) whose job was to pray in the church across the road.

The Hornchurch brethren were French. That seemed to explain why the coins had been buried.

Forcing a civil war in 1264-65, a nobleman called Simon de Montfort challenged Henry III’s unpopular French advisers, notably Peter of Savoy.

Although French himself, de Montfort stirred English resentment against foreign influence.

Fearing attack, it seemed the canons had buried their cash for security.

But why hide the coins beside a road – and in a hole only 18 inches deep? And why did they never dig up their money when quieter times returned?

Richard de St Sulpice, Master of Hornchurch Priory from 1257 until 1281, had plenty of time to recover the priory’s treasure, or to tell his brethren where it was hidden.

I believe the Hornchurch coin hoard tells us about a burglary, an insider job that went wrong.

You didn’t get much sleep in the religious life. Canons attended half a dozen services every day.

At midnight and again before dawn, the black-robed brethren would walk in procession to chant their prayers in St Andrew’s Church.

Somebody working at the priory must have discovered where the holy men stored their cash (there were no banks in those days).

The canons’ absence at prayer gave just enough time for stage one of the heist.

The coins were probably scooped into a couple of sacks, which had rotted long before 1938.

But there wasn’t enough time to get the loot safely away.

So it was buried, in a shallow hole, quickly dug beside the road where it could be recovered later.

But something went wrong. Stage two of the daring crime never happened.

Maybe the burglary was discovered right away – and the obvious suspect promptly hanged for theft.

Havering conducted executions at Gallows Corner. In 1285, the priory claimed the right to its own gallows at Suttons. Hanging people was easy.

Perhaps the offender fled, and never dared return.

Maybe he failed to remember precisely where he’d buried the sacks that dark night. We’ll never know.

We can even narrow down the date of the crime. A new “moneyer” (coin-maker) took over a London mint in May 1260. The hoard contained just one of his coins. In July 1261, the king exempted Hornchurch priory from paying tax – a sign that the brethren were hard up.

That dates the theft to the winter of 1260-1.

The crime was a terrible blow. Peter of Savoy gave Hornchurch Priory a valuable London property. In 1270, the brethren were forced to sell it. The Savoy Hotel occupies the site.

Poverty dogged the small priory until it was closed in 1391.

Ironically, the stolen treasure was there all the time, under the feet of the holy men as they made their stately way to prayer.