A British judge grabbed a convicted sex offender by the throat and pinned him to the floor to stop him escaping from court, a trial heard on Tuesday.

Judge Douglas Marks Moore, 60, wrestled 34-year-old Paul Reid twice as he attempted to flee from Woolwich Crown Court in London last August.

Reid made his desperate bid for freedom after giving evidence in his trial, jurors at the Old Bailey, the central criminal court in London, heard.

"One thing stood between Paul Reid and freedom -- the judge trying his case," said prosecutor Rupert Gregory.

"As he went through the door his honour Judge Marks Moore grabbed him round the throat to try to bring him down.

"Together they went down three steps and then Mr Reid broke free and ran down the judge's corridor.

"The judge gave chase. Just as Mr Reid was about to open a push-handle fire door, HHJ Marks Moore rugby-tackled him around the throat and waist and brought him crashing to the ground, landing on top of him.

"He held him there, struggling and protesting, until the prison officers managed to catch up, secure him and return him to custody."

The 34-year-old Reid is now standing trial for escape and attempted escape, both of which he denies.

The case continues.

-AFP