Eagle-eyed motorists driving along High Road in Bushey Heath will not have failed to have noticed a bright yellow police van with a CCTV camera parked in the Tesco Express Esso petrol station.

Residents and shopkeepers have been calling the newsdesk repeatedly asking why it is the van has been left in the garage for several hours a day, for more than a month.

When the Watford Observer asked police why it was stationed there, they refused to give a specific answer.

Hertsmere Chief Inspector Dean Patient said: "We have a responsibility to reduce and deter crime and we will seek to deploy our resources in key locations all over the county in order to meet this purpose.

"We are not willing to discuss the reasons for individual deployments however they are all related to on-going crime reduction and detection work. "No police assets would be left at a particular place without good reason."

But a conversation with staff from Tesco Express revealed that the van is there to stop motorists driving off without paying for petrol and to track motorists with false number plates and invalid tax or insurance.

Karan Theyeagearasha, deputy manager., said: "We’ve had loads of people come in here, fill up their tanks and drive off.

"It’s not a small amount of petrol either, we’re talking at least £70 a time.

"Having the police presence acts as a deterrent, they’re preventing crime.

"If people drive in with false number plates, without insurance or valid tax, or even stolen cars they can capture them on their CCTV."

They park up on the forecourt and leave the van there, it’s not like they are sitting in there all the time on a long lunch break, relaxing. And they’re not always here; it’s quite random when they visit.

"They might come in and buy some lunch from time-to-time, but they leave the van and then patrol up to the High Street.

"They are killing two birds with one stone, they’re doing two jobs. Not only are they ensuring motorists are abiding by the law, they are taking to the streets to ensure no crime is committed - it’s a great way to combat crime.

"Since they’ve started doing it I’ve noticed fewer people are driving off without paying for their petrol.

"What they are doing is a great thing for the community, it’s creating a sense of safety in the area."