Retired engineer Mike Osborn had no idea he'd be king of the castle when he moved to Malmesbury from Devon.

The 68-year-old from Avon House in Abbey Row, bought the Georgian Grade II listed building six months ago so that he and his wife could be nearer their family.

But it turns out that the property may stand on the site of a 12th century castle.

Mr Osborn was unaware that his house may have such a distinguished heritage until he applied for planning permission last month to extend his garage and alter his utility room.

Town councillors supported his application but requested that the county archaeologist keep a watching brief during the excavations.

Mr Osborn said: "The property brought us to Malmesbury. We fell in love with it and the town.

"We didn't know much about the background of the house."

Town councillor and local historian Charles Vernon thinks the Osborns' house is probably on the castle site. He said: "Malmesbury had a castle for about 100 years between 1120 and 1216. It was built by Bishop Roger of Sarum who also built Devizes Castle. He built it to upset the monks in Malmesbury Abbey.

"Around 1153 it was the site of a battle between Empress Matilda and King Stephen and eventually the monks pulled it down."