Post-Roman tombstone from Cornwall

Fascinating, probably 6th Century tombstone, from Railton Barton, St Columb Minor. It is now in the Royal Cornwall Museum in Truro.

The top of the stone with the name of the person buried is missing.

The early 6th Century Latin inscription reads: BONEMIMORI [missing name] (F)ILLI TRIBUNI which translates as "in loving memory of [name], of a son of Tribunus.

This crude inscription dates from well after the Roman Imperial evacuation of Britannia in 410 and so shows the survival of Latin as a written language for at least a century in the far South West, where it is thought the pre-Roman tribe of the Dumnonii re-established an independent kingdom in what we now call Devon and Cornwall.

The other interesting point is the name Tribunus, which is of course the military title of the commander of a later Roman military unit - a tribune. So can we infer that the ancestors of the person buried here had been a Roman military commander who stayed on in command of his unit and became a leader of the post-Roman Dumnonian kingdom?