A mediaeval chess piece missing for almost 200 years could fetch £1m (R18m) at auction after a family found that the object they kept in a drawer is one of the long-lost Lewis Chessmen.The Chessmen – a famous hoard of 93 objects – were found 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 (R90) in 1964 is one of the missing treasures.The Edinburgh antique dealer had no idea of the significance of the 8.8cm piece, made of walrus ivory, which he passed down to his family.They 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, said his jaw dropped when he realised what it was.“I said: ‘Oh my goodness, it’s one of the Lewis Chessmen’.”The Lewis piece will go up for auction in the Old Master Sculpture & Works of Art sale at Sotheby’s in London on July 2.