A “scarce historical treasure” which dates back 1,000 years to the time of William the Conqueror is set to fetch thousands of pounds when it goes under the hammer next week. 

The medieval bishop’s seal was discovered amid hundreds of objects massed by a Norfolk metal detectorist over 40 years.

Now it has been tipped to spark an auction bidding battle. 

The scarce copper alloy seal matrix shows a bull being attacked by a lion and bears the inscription, WILLEMI DE MARTHAM – the seal of William of Martham, the Broads village near the coast which once sat on an island, the Isle of Flegg.

Eastern Daily Press: This ancient seal, seen with its wax imprint, is thought to have belonged to the  Bishop of

Research indicates he was Bishop of Thetford in 1085, and the son of Robert Sire de Belfou who fought for William the Conqueror at the Battle of Hastings in 1066.

The seal will be offered by Hansons Auctioneers on January 30 with a guide price of £1,500. However, it’s expected to soar past its estimate due to its historical importance. 

A spokesman for Hansons said: “Items like this are rarely unearthed so they’re desirable. 

Eastern Daily Press: Bayeux Tapestry featuring  William the Conqueror discussing Norwich Castle

“A previous clergy seal belonging to the Archbishop of Canterbury achieved £5,600 at Hansons but this new find pre-dates that by 300 years.

“It’s circa 1085, the time when the Bishop of Thetford was granted Martham, a village in Norfolk. This was during the time of William the Conquer who died in 1087.

“It could surprise us under the hammer because bishop’s seals simply don't come up often. It’s a scarce historical treasure and we owe its discovery to one man’s historical passion.” 

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The find is part of a lifetime collection of more than 1,000 objects amassed over 40 years by a metal detectorist from Thetford.  

Following his death, his wife has parted with his finds to ensure they live on as mementos of history.

They include hammered medieval coins and numerous ancient artefacts which have taken months to sort and catalogue hundreds of items. 

Eastern Daily Press: The  valuable seal , centre, was spotted amid a vast collection of metal detecting finds

The spokesman added: “His passions in life were nature, wildlife and metal detecting.  

“He loved anything ancient. He had a particular interest in the Saxon era and medieval seals.  

“He enjoyed researching the objects he found and developed a deep knowledge of history.  

"The seal must have been one of his most prized possessions.” 

The Single-Owner Historica Auction will be held at Hansons Auctioneers’ Derbyshire saleroom on January 30.

Eastern Daily Press: The wax imprint from the seal, made by its late owner. Seal thought to  belong to the  Bishop of