A MEDIEVAL chess piece missing for almost 200 years could fetch £1 million at auction after a family found out the object they kept in a drawer is one of the long-lost Lewis Chessmen.

The Chessmen – a famous hoard of 93 objects – were discovered in 1831 on the Isle of Lewis. The whereabouts of five pieces from the collection had remained a mystery.

A family has now been told the late 12th or early 13th century chess piece their grandfather bought for just £5 in 1964 is one of the missing treasures. The antiques dealer, from Edinburgh, had no idea of the significance of the 8.8cm piece, made from walrus ivory, which he passed down to his family.

They have looked after it for 50 years without realising its importance, until they took it to Sotheby’s auction house in London.

The Lewis Chessmen are among the biggest draws at the British Museum and the National Museum of Scotland in Edinburgh.

They are seen as an “important symbol of European civilisation” and have also seeped into popular culture, inspiring everything from children’s show Noggin The Nog to part of the plot in Harry Potter and the Philosopher’s Stone.

Sotheby’s expert Alexander Kader, who examined the piece for the family, who wish to remain anonymous, said his “jaw dropped” when he realised what they had in their possession. He said: “We get called down to the counter and have no idea what we are going to see. More often than not, it’s not worth very much. I said, ‘Oh my goodness, it’s one of the Lewis Chessmen’. It’s a little bit bashed up. It has lost its left eye. But that kind of weather-beaten, weary warrior added to its charm.”

A family spokesman said in a statement: “My grandfather was an antiques dealer in Edinburgh, and in 1964 he purchased an ivory chessman from another Edinburgh dealer, presumably unaware he had purchased an important historic artefact. My mother inherited it and for many years it resided in a drawer in her home.”

The Lewis Chessmen are made up of seated kings and queens, bishops, knights and standing warders and pawns. Some 82 pieces are in the British Museum and 11 are held by the National Museum of Scotland. As well as the chess pieces, the hoard includes 14 “tablemen” gaming pieces and a buckle. Since the hoard was uncovered in 1831, one knight and four warders have been missing from the four combined chess sets.

The newly discovered piece is a warder, a man with helmet, shield and sword and the equivalent of a rook on a modern chess board, which “has immense character and power”.

The discovery of the hoard remains shrouded in mystery. It is thought it was buried, possibly by a merchant to avoid taxes after being shipwrecked, soon after the objects were made and so remained underground for 500 years.

Kader, who has kept the discovery under wraps for six months while authenticating the find, said: “We can safely say that a million pounds will transform the seller’s life.”

He added: “There are still four out there somewhere. It might take another 150 years for another one to pop up.”

The piece will go on display in Edinburgh today and in London just before the auction.