The £500,000 target

An ancient gold cup owned by a scrap metal dealer is expected to fetch around £500,000 at auction after languishing for years in a shoe box under its current owner's bed. Owner John Webber says his grandfather gave him the 5.5-inch (14-centimetre) high mug to play with when he was a child, back in 1945.

He assumed the golden cup, which is decorated with the heads of two women facing in opposite directions, their foreheads garlanded with two knotted snakes, was made from brass but when he got it valued in 2007 he was told it was actually a rare piece of ancient Persian treasure, beaten out of a single sheet of gold.

Experts said the method of manufacture and the composition of the gold was "consistent with Achaemenid gold and gold smithing" dating back to the third or fourth century BC.The Achaemenid empire was wiped out by Alexander the Great in 330 BC.

Webber, 70, stated that his grandfather had a "good eye" for antiques and picked up "all sorts" as he plied his trade in Taunton, Somerset"Heaven knows where he got this, he never said," he added, revealing that as a child, he used the cup for target practice with his air gun.