It took just five seconds for a thief to smash his way into a car parked in the centre of Oxford, and make off with a haul of presents in broad daylight.

Thames Valley crime reduction adviser Nick Gilbert staged the stunt in busy Broad Street to ram home a crime prevention message.

And he was startled that shoppers walking past didn't bat an eyelid as he smashed the side window of a Rover, and helped himself to presents piled in full view on the back seat.

Some were shocked but still moved on, while others even laughed.

"It was a real eye opener," said Mr Gilbert, who spurned wearing a suspicious-looking hoody or baseball cap, preferring ordinary black coat, scarf and woolly hat.

"There must have been hundreds who saw what was going on. They were just streaming past with their shopping."

An hour later at the city's Worcester Street car park, the stunt produced a similar reaction.

The three cars used in the police and city council operation were scrap vehicles, but the method used by Mr Gilbert was one commonly used by thieves - a small hammer hit against a side window, breaking the glass and allowing easy entry.

And in just five seconds he was off with his haul - a teddy bear and perfumes loaned by Boswells and Debenhams for the demonstration.

It highlighted a serious lesson for shoppers, particularly at Christmas, of how easy it is to lose presents when they are left in an unattended car.

"First of all, when you are going out shopping, do not leave anything on display in your car," Mr Gilbert said.

The exercise is similar to one mounted in Oxford just before Christmas last year when police showed how easy it is to steal a bike using disc cutters.

Because of the publicity, reporting of incidents went up and actual bike thefts in the city went down in the immediate aftermath.

Mr Gilbert added: "Overall, car crime in the city is reducing but people still need reminding in a dramatic way that they could be victims - and that they can take action by reporting things. It was just not good enough to walk by as if nothing was going on."

People who see car crime being committed should ring 999. Witnesses should call 08458 505505.