WHEN BRIAN Malin's metal detector emitted a faint beep on a spring evening two years ago, he would have had little idea that his discovery, far from adding a footnote to local history, was about to rewrite that of the ancient world.
Inside the 1,700-year-old earthenware pot that Mr Malin discovered was a small base metal coin that has revealed the existence of a hitherto unknown emperor who ruled Britain and much of western Europe amid dark tales of rape and murder.
The base metal silver "denarius", barely the size of the 20p piece, uncovered by Mr Malin, 32, a factory supervisor from Chipping Norton, Oxfordshire, went on show yesterday at its new permanent home, the Ashmolean Museum in Oxford, 10 miles from the field where it was dug up in April 2003.
The unveiling completed a journey of nearly two millenniums for the coin from a Roman mint in Germany to the farmland of ancient England, where its presence confirmed the existence of Domitianus - a forgotten Caesar whose reign in a period of bloody turmoil was so fleeting that he has been called the Four-Day Emperor.
Richard Abdy, the curator of Roman coins at the British Museum, who first spotted the coin as he separated it from a mass of nearly 5,000 found fused together in Mr Malin's pot, said: "It is an exceptionally rare coin. What this small coin establishes is that we now have a new emperor who is not mentioned in the history books.
"His reign, probably because it was so brief, has gone undocumented in his own era. But because of what was found in a field so many years afterwards we can shed new light on a fragmenting Roman empire."
The coin shows a likeness of Domitianus, or Domitian, in profile wearing a crown of rays with an inscription confirming his status as emperor - Imp(erator) C(aesar). It is probably not an accurate portrait, since it is similar to both his predecessor and his successor.
On the reverse is a figure with the words "Concordia Militum". Concordia stands for agreement and harmony and the figure is a traditional statement of loyalty to the army, to whom so many Roman emperors owed their power (and indeed their lives) and from whose ranks Domitianus possibly rose as a general in the praetorian guard.
But rather than being a Caesar anointed by Rome, Domitianus was the ruler of a vast breakaway sector of the Roman empire encompassing modern-day France, Germany, Britain and, initially, the Iberian peninsula. …