Gold coin proves 'fake' Roman emperor was real

An ancient gold coin proves that a third century Roman emperor written out of history as a fictional character really did exist, scientists have said.

The coin bearing the name of Sponsian and his portrait was found more than 300 years ago in Transylvania, once a far-flung outpost of the Roman empire.

Believed to be a fake, it had been locked away in a museum cupboard.

Now scientists have said scratch marks visible under a microscope prove that it was in circulation 2,000 years ago.