An alert witness photographed a gang of jewel thieves as they fled a shop with £38,000-worth of gems and watches.

Chartered surveyor Nick Bradbeer was praised by a judge yesterday, along with another man, engineer Ian Povey, who noted down the number of their getaway car.

Police were on the gang's tail moments later. A 120mph chase through Sussex ended when the gang tried to drive through fields and crashed.

Mr Bradbeer said he spotted three men hanging around outside Goldsmiths Jewellers from his office opposite the shop in Castle Square, Brighton, in June.

The men forced their way into the jewellery store when two frightened female shop assistants refused to open the door after watching the raiders trying to get in three times on security camera monitors.

The women fled terrified after three of the men kicked the front door in and stuffed watches and jewellery into two bags.

Mr Bradbeer, 44, said: "The jewellers had been robbed twice before and I gave descriptions to the police at the time.

"It is always difficult to describe people so I thought I would try to take a picture if it ever happened again."

Mr Bradbeer, a senior partner with commercial property agents Stiles, Harold, Williams said he became suspicious when three men kept returning to look in the window of the jewellery shop."

Mr Povey took the number of the gang's Mercedes four-wheel drive vehicle as it sped from the scene.

The gang crashed the car in a field near Ansty and fled on foot into dense woodland, dropping bags containing the watches and jewellery.

A search by helicopter, police dogs and officers on foot resulted in the arrest of three men.

Victor Stirling, 22, of Malvern Way, Thornton Heath, Surrey, and Shaun Springer, 22, of Northway Road, Croydon, both pleaded guilty to commercial burglary and appeared for sentence yesterday.

A third man, Sean Marratt, from London, denied the same charge and was cleared at his trial on the direction of the judge.

Byron Williams is wanted by police in connection with the raid.

Andrew Judge, defending, said Stirling had gone with the others for what he believed was a day out to Brighton on June 21.

He said they had spent the afternoon window shopping and had been on the beach before they went to Goldsmiths in Castle Square, which has closed since the raid.

The judge, Recorder Ian Wilson, jailed both men for three years and ordered Springer to serve 238 days remaining of a previous sentence for two burglaries in 2000 for which he had been released on licence.

He said: "I would like to commend Mr Bradbeer and Mr Povey for their spontaneous public-spiritedness, which played a large part in bringing these two men to the attention of the police."