IT may not be a pot of gold, but one artefact at an ancient stone fortress has shed new light on an unusual example of Yorkshire thrift.

Archaeologists at the 950-year-old Richmond Castle have revealed that, even in times of medieval conflict, absolutely nothing went to waste.

Experts believe that a fifteenth century jug, now on display, was an easy source of income for crafty soldiers.

The jug is believed to have been a primitive form of urinal for military chiefs, who would sell its contents as an ingredient for leather tanning.

The artefact is among an array of relics exhibited at the castle's new £500,000 exhibition and visitor centre.

Senior curator for English Heritage, Andrew Morrison, said the jug had historians intrigued when it was recovered from a well in the castle during an excavation in the 1930s.

He said soldiers, aware of the acidic value of urine would sell gallons to local tanning merchants.

"Everybody would have been doing this to earn extra money but you don't often find them so complete and datable," he said.

The tenth Duke of Richmond, returned to the seat of his titled ancestors to unveil the new museum.

The exhibition traces the fortress's history back to its foundation in 1071.

It also includes a full-size prison cell used by World War One pacifists, with recreations of inmates' wall art explaining their objections.

English Heritage regional director, David Fraser, said: "We are delighted that the Duke of Richmond has agreed to open this ambitious new exhibition and visitor centre.