Treasure hunter Tony Mims wants townspeople to help him unlock the history behind a silver medieval ring he discovered on a Malmesbury farm.

Mr Mims, a 48-year-old lorry driver from Pinewood Way, Colerne, unearthed the 15th century ring with his metal detector in August 2003. He knew instantly it was special, and tomorrow a treasure inquest will judge if a Devizes museum should buy it for the public.

Mr Mims said: "I found it on a farm outside Malmesbury. The farmer has lots of fields and this was the last one I tried. He told me there had been a medieval village down there, and straight away I found a brooch. About 6ft away, I found the ring about three or four inches down the soil."

The ring has initials and a seal which suggests a merchant owned it.

Mr Mims has been metal detecting since 1974. He has found coins, and buckles dating from the Roman and medieval periods in the Malmesbury area.