STAFF at the Galleries of Justice believe Robin Hood could have been imprisoned there after archaeologists uncovered what may be a medieval dungeon.

Dr David Walker and Pauline Armstrong, from the Trent and Peak Archaeological Unit at Nottingham University, have examined the bottle-shaped cave deep underground.

Now supporters of the theory are pointing to a ballad telling how Nottingham's most famous son was cast into a pit close to St Mary's Church.

Dr Walker said: "The cave could be an oubliette, which is French for a forgotten place.

"They would put somebody down there with a rope or ladder and there is no way they could get out."

Prisoners could be shut in and left to starve in the pit, or kept alive in solitary confinement.

Tim Desmond, the attraction's chief executive, said it was now possible dungeons mentioned in the 15th century tale of Robin Hood and the Monk could be have been under the Galleries.

He said: "It is quite exciting. Robin Hood is built on legend but we want to get to the history. The King's Hall was used by the original Sheriffs of Nottingham, we can't argue with the historical facts."

Dr Walker said it was also possible that the bottle-shaped cave might have been used for storage. But the site's history as a place of crime and punishment meant it might well be an oubliette, similar to the one at Newark Castle.

He said: "They are quite rare. That doesn't mean it's not a storage cave, but given its position as deep as it is and what we know about this building, it being a dank and dismal oubliette is not impossible.

"We definitely could do more work here."

Managers at the Galleries are hoping a full investigation of the site could provide links back to the days of the legendary Sheriff of Nottingham, and even the Anglo-Saxon period. The earliest record of a Sheriff on the site dates back to 1129 and it is known that prisoners were tried and hung on the site from the 1300s.

Gary Holmes, the general manager of the former courthouse, said punishments could have been meted out even earlier.

He said: "There were Sheriffs before 1129 and, if there was a place of crime and punishment, it is going to be this site."

Ms Armstrong said she was keen to explore a second sandstone cave previously used as a store and a collapsed tunnel which could join up to the city's underground caves network.

She said: "What's interesting here is not just that it has been used over a long period of time but that it has been left alone. Pots are just lying on the surface, it's not been used for years."

Dr Walker said it would be difficult to give a date for when this second cave was first used without further exploration.

He said: "It's very difficult to date caves. At first look, it seemed like a storage cave. It could have stored barrels.

"But there's certainly nothing to say it isn't Anglo-Saxon."

Mr Holmes said he hoped to secure funding to allow the team to dig trenches to explore Nottingham's ancient past.

He said: "There is an opportunity for tourism. We have the Castle but that is far more recent history.

"We need to explore the city's pre-Norman and Medieval past and I absolutely believe this is the key to that time.

"We have lost a lot of it, but this is a fantastic opportunity to explore some of the history of Nottingham.

"This work is important if we are serious about the history of the city. A lot of it is essential to get us better knowledge."

The Galleries of Justice has recently launched a new feature on the Sheriffs of Nottingham.

sarah.firth@nottinghameveningpost.co.uk