IT HAD lain undiscovered and untouched for almost 2,000 years and could have been lost forever if not for the persistence of an amateur archaeologist and his camera phone.

Joiner Larney Cavanagh instinctively knew he had found something special when he and his 10-year-old son happened upon a Latin-inscribed artefact in a field near their East Lothian home.

What they did not realise was that they had discovered the first Roman tombstone in Scotland for 173 years.

But Cavanagh's attempts to alert archaeological experts to the find were treated with scepticism until he sent them pictures of the metre-long object from his mobile phone.

They then launched an investigation which concluded that the memorial was one of the most important discoveries of recent times, and provided a fascinating insight into the life of a Roman cavalryman.

Cavanagh, 34, spotted the red sandstone tombstone at the edge of a field at Carberry, near Inveresk, on a expedition inspired by his son Tyler's school project on the Roman Empire.

"I knew it was something significant," he said. "My heart started racing and I felt my jaw drop. I'm not sure who was the most excited, me or my son.

"We ran all the way to my brother's house and phoned a local archaeologist and the National Museum. They told me they were kind of busy and that they would maybe have a look at it the following week."

Cavanagh, of Whitecraig, near Musselburgh, then sent them a series of images from his camera phone.

"Suddenly the phone started ringing off the hook when they realised how important my find actually was," he said. "They made arrangements to come and see it the very next day.

"We were delighted to have it confirmed that it was a Roman tombstone and was hugely important. Tyler couldn't wait to tell his teacher about what we had found. We are both proud to have found something that is going to be put on display in a museum for hopefully hundreds of years to come.

"It's not bad for a bit of homework."

The tombstone is the first to be unearthed north of the Border since 1834. Dating from between 140AD and 180AD, it features the image of a Roman cavalryman charging down a native Caledonian.

The inscription shows it was dedicated to the memory of a man named Crescens, who was a mounted bodyguard for the imperial governor who ran the occupied parts of Scotland, England and Wales.

It reads: "To the shades of Crescens, cavalryman of the Ala Sebosiana, from the detachment of the governor's bodyguard (the Equites Singulaires), served 15 years, his heir (or heirs) had this erected".

Dr Fraser Hunter, principal curator of Roman archaeology with National Museums Scotland, said: "Tombstones like these are surprisingly rare in Scotland, given that there was a garrison of several thousand men here over a period of more than 50 years. Only 13 have ever been found. This is the first time we have found evidence of the governor's bodyguard in Scotland.

"It is also a fantastic potted history of this man's life and career and shows that he was a well respected and important man.

"The image is fairly typical in that it shows a so-called barbarian, displayed as being naked and hairy, being overcome by a noble Roman soldier.

"It is very much a work of propaganda. Stones like these were there to celebrate the achievements of individuals in the Roman army, but were also there to intimidate people and act as a warning.

"There is a lot of cleaning work still to be done on the stone but eventually it will be put on public display."

Hunter believes the presence of the stone near Inveresk suggests that Crescens died while accompanying the governor on a visit to the fort there.

Biddy Simpson, archaeologist with East Lothian Council, said: "This is an incredibly exciting and rare find and we are indebted to the finder for bringing it to our attention so swiftly. This type of find highlights the wealth of archaeological remains in East Lothian and emphasises how the county has played a pivotal role throughout pre-history and history."