The battered scraps of metal discovered by Tom Redmayne, an amateur metal detector, in a muddy field in Lincolnshire are a unique find.
The mid-fourth century was a time of turmoil in Roman Britain. A Roman aristocrat, Valentinus, had been exiled to Britain where he was stirring up trouble.
Thousands of Roman cursing charms survive, scrawled on pieces of lead with a hole punched to hang them up. Many were found thrown into the hot springs in Bath, demanding revenge on those guilty of petty theft.
Nothing as audacious as cursing an emperor has ever been found before. However, Sam Moorhead, a coins expert at the British Museum and expert adviser to the Portable Antiquities Scheme, which encourages voluntary reporting of finds, is convinced it is the only explanation.