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

The Lewis Chessmen - a famous hoard of 93 objects - were discovered in 1831 on the Isle of Lewis in the Outer Hebrides.

But the whereabouts of five pieces from the collection have remained a mystery.

A family has now been told the 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, before bringing 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, said that his "jaw dropped" when he realised what they had in their possession.