Watch: Dig revealing secrets of Oswestry Castle

The heritage dig at the castle has already reaped rewards with volunteers finding an old musket ball.

Work got under way on the Oswestry Castle Research Project after a £7,400 grant from The Heritage Lottery Fund. A smaller grant came from the Borderlands Rotary Club.

The dig has coincided with the events taking place in and around the town to mark National Heritage Open Days.

Excavation is concentrating on two large trenches close to the remains of a wall on top of the motte and bailey castle behind Oswestry's Guildhall.

Roger Cooper, project director, said: "Last year we were excavating material from the large trench that we think is demolition rubble from the destruction of the castle. We did not reach a medieval floor level but this year we hope to do just that and reveal the floor as it may have been in the middle ages.

"If we reach this level we hope to find items such as coins or pottery. This will be a minimum of a five-year project – little is known about the castle. We want to develop our knowledge of the site, which was a very important 'Marches', or border, castle."

The dig will continue until Friday.