A POST Office delivery man was threatened with a pistol gun by a masked raider as he entered Walcot Post Office with a secure box containing cash.

The robber held a pistol to the man's eye.

The Post Office is offering a substantial reward to find one of the two robbers involved, who was still at large last night.

The other thief was caught by the police after driving 50 miles from Swindon to Stratford-upon-Avon, where he was arrested.

Wearing blue boiler suits and ski masks, the two men forced the delivery man out of the post office, based in Forbuoys newsagents in Sussex Square, at 9.05am yesterday (Friday).

A witness, who asked to remain anonymous, said: "It was like something out of a movie. I saw a man with a silver gun and he was hitting the delivery man. I couldn't believe it."

The offenders tried to steal two secure red boxes, which were in a Post Office van parked at the back of Forbuoys.

One of the boxes they snatched came open, releasing a cloud of red smoke.

Grabbing the other box, the men leapt over a wall behind Forbuoys and fled in a champagne coloured Seat car.

A Post Office worker called the police, who arrived at the scene within two minutes. The delivery man was uninjured but frightened by the ordeal.

Nick Barnard, 39, from Walcot, said: "I was just popping out to the shops and heard police sirens. The same thing happened there nearly 10 years ago.

"Now we have CCTV cameras here, you don't expect armed robberies."

Police patrols across Swindon were alerted and, thanks to reports from the public, found the getaway car abandoned in a garage in Oaksey Road, Penhill.

Discarding the secure box, the 22-year-old male driver and his accomplice ran to another car, a blue Ford Focus, nearby and continued their escape.

They travelled north on the A419 towards Gloucestershire. Witnesses helped the police to trace the car, which was followed using cars and helicopters.

As the offenders travelled towards Warwickshire, police in Swindon sealed off the crime scenes and took the Seat and secure box away for forensic testing.

The Ford Focus stopped in an industrial estate in Stratford , where police arrested the driver and discovered that his accomplice had left the car at some point during the journey.

The driver was last night being interviewed by Swindon police, who were still searching for his passenger.

Inspector Bob Walton said: "We are very pleased with the speed and success of our response.

"The public were very cooperative with our enquiries. We would like to reassure them that incidents of this nature are extremely rare."

The Post Office is also assisting the police with their inquiries.

Dan Panes, Post Office spokesman, said: "We are investigating the incident and offering a reward for any information that leads to a conviction."