The unusual object was used to hold plants at the Stocks Arms, Northowram, Halifax, more than two decades ago.

It was claimed by regular Peter Deeks when the pub – which has now closed down – changed hands.

The retired policeman has spent his time ever since trying to work out what it was and finally after taking it to Bankfield Museum in Boothtown, Halifax, has been told it was a Victorian replica of the Anathema Cup – complete with an ancient curse inscribed on it.

Archaeologist Amy Cooper, of the Portable Antiquities Scheme which is managed by the British Museum and works with experts from West Yorkshire Archive Service, said: "It was puzzling. It looked old in style but it wasn't.

"It took some detective work but it turned out to be a Victorian copy of the original Anathema Cup. It was common in Victorian times to make copies of objects so that people around the country could see them on display and not just in one place."

The original Anathema Cup is held in Pembroke College, Cambridge, and is thought to have been made around 1460.

It was given to the college by Thomas Langton who died of the plague just before he was due to be ordained as Arch-bishop of Canterbury.
It is thought that six copies were made in 1879 but it is not known how this one ended up in Halifax.

The cup had an ancient inscription on it which staff at the West Yorkshire Archive Service were asked to decipher. It translates as: 'Whoever shall take it away, let him be cursed."

Mr Deeks, 55, who lives in Northowram, said: "I didn't know what it was all about. I've spent years asking people what it was.

"I read an article in the Courier and went down to Bankfield Museum with the cup to see if they could unlock the mystery."

Mr Deeks said he was not completely happy to solve the mystery: "I thought I had the Holy Grail so I was a little disappointed to find out I had a cursed cup.

"I might have to leave it in the garage and not the house from now on just to be sure."

Cup facts

The Anathema Cup is so called on account of the threatening inscription which it carries. Scholars have translated it as: 'Thomas Langton Bishop of Winchester formerly Fellow of Pembroke Hall gave this covered cup to the same Hall 1497: whoever shall take it away let him be accursed LXVII ounces.'

The cup is made of silver but is coated in gold.

The hall mark on the cup is that of 1481–82, but the actual date of manufacture is about 20 years earlier.

Six copies of the cup are thought to exist with only four of them accounted for so far.