The first Roman tombstone to be found in Scotland for more than 170 years has been uncovered by an amateur archaeologist.

Dating from between AD40 and AD180, it is believed to mark the grave of Crescens, a bodyguard for the Roman governor.

The red sandstone tombstone was found by a joiner, Larney Cavanagh, 34, in a field at Carberry, near Inveresk in East Lothian.

He was with his 10-year-old son when they came across the stone with a Roman inscription on it.

Mr Cavanagh said: "I was stunned when I laid eyes on the stone, and very nervous as I awaited confirmation of my initial suspicions.

"Some finds are difficult to recognise at first as being significant, but this one was instantly recognisable."

The stone, one of only 13 ever found in Scotland, has an image of a naked barbarian, apparently dead. Most of its upper part is lost, but experts said a surviving hoof and foot indicate that it would have shown a cavalryman attacking the barbarian.

The find has been described as one of the most important for years, and is the first Roman tombstone found in Scotland since 1834.

The stone strongly suggests that Crescens died while accompanying the governor on a visit to the fort at Inveresk, evidence that it was a pivotal roman site in northern Britain.

Dr Fraser Hunter, principal curator of Roman archaeology with National Museums Scotland, said: "It is very rare to find Roman tombstones, and this is the first evidence of the governor's bodyguard in Scotland.

"The cavalryman riding down a barbarian, who represents our unfortunate Scottish ancestors, is a typical image seen on tombstones all around the frontiers of the Roman Empire, but this is the first Scottish example ever found."

The stone is being examined at the National Museums Collection Centre in Edinburgh.