Just one person dialled 999 after a “thief” was seen breaking into a car during an undercover police operation.

During the staged heist – dubbed Operation Jugular – plain-clothed policeman Pc Simon Collins broke into a green Rover in High Street, Witney.

As he ran off with a laptop and mobile phone, just one man pushing a buggy gave chase and called the police.

In the past year thefts from vehicles have risen in west Oxfordshire by 32 per cent. In 2008, there were 59 offences, but this year has seen 78 thefts.

Pc Collins hoped the operation would encourage people to call the police if they see something suspicious.

He said: “The gentleman who followed me with a pushchair was really brave to do that with his child.

“Quite a few people noticed but kept themselves at a distance. I honestly thought we probably wouldn’t hear of anyone calling it in.”

Pc Collins, dressed in a red T-shirt and khaki shorts, started at Waitrose car park, in Witan Way, where he tried the handles of car doors. Nobody reported this to the police.

The policeman’s description was then radioed through to approximately 20 shops and pubs, asking staff to keep an eye out for him.

When Pc Collins reached High Street, he targeted a car left by officers with a window open and a mobile phone and laptop visible inside.

He broke into the car, set off the alarm, and ran off with the items.

Mark Thomas, 33, who was with his toddler son, followed the fake crook, along with a grey-haired woman, and called the police.

When shown Pc Collins’s ID, Mr Thomas, of Witney, said: “I had been in the Millets store and heard a description of him on the radio.

“I was walking down the road and when I heard the alarm go off, I thought I’d see where he went. I was not going to confront him.”

Despite the many passers-by, Mr Thomas was the only one to dial 999.

Taxi driver Julian Taylor, 50, of Hook Norton, heard the car alarm.

He said: “He did look suspicious – he just got out and ran up the road. Being a taxi driver, if you see something suspicious, you do ring ‘999’.”

Pc Phil Marstin, auto crime co- ordinator for west Oxfordshire, said: “I think it highlighted how easy it is for somebody who doesn’t look like a thief to get away without anybody challenging him.

“We are not saying that everybody needs to be a hero, but people need to be aware and if they think something is suspicious, call the police.”

Officers working on Operation Jugular will be at the Market Square in Woodstock on Thursday.

From 12pm until 3pm, people can find out how to secure their home and learn about personal crime prevention.