A seven-year-old boy whose cat was killed by a car outside his home has been busy policing drivers by giving them a “stern glare."

Harry Cannell, from Mattishall, Norfolk, England, keeps an eye on traffic going past his home — waving at those going the correct speed and glaring at anyone going too fast.

His efforts came to the attention of two local police officers, who let him try on their uniform and test out the speed gun.

Harry spent some time with two local officers, who showed him how to use the speed gun (Claire Cannell)

It came after the Cannell's family cat Trevor was run over last month on the 30mph road outside their home, and Harry became concerned about speeding.

The family put up a large sign to warn drivers and Harry spent his time scowling at motorists in his hi-vis vest.

Harry's mom, Claire, told the PA news agency:

“Harry was counting down the days to their visit, he was so excited."

“They showed him how to do speed checks and how to use the speed gun. They even brought him a little uniform to wear. They put a little jacket on him and a hat and showed him everything in the car."

“For the rest of the day he was just beaming from ear to ear, he had to phone all the grandparents and tell them."

Harry, who aspires to be a police officer when he is older, said:

“I would like people to listen, and stop being idiots."

Trevor is the second pet belonging to the family to be killed on the road in the last four years.

Harry said his favorite part of the day was using the speed gun (Claire Cannell)

Mrs. Cannell said:

“The road here is pretty dreadful. Even though it is a little country lane, because people use it as a rat run through the village, people just absolutely tear down here."

“We've been here four years and had four separate accidents with our cats. It's got to the point where we can't have any more cats because it's just too upsetting to lose them."

It was after she posted on the local Facebook noticeboard, two officers got in touch and asked to come down and meet Harry.

Posting photographs of Harry working with them, Breckland Police wrote on Twitter:

“Harry has been encouraging road safety and speed awareness on his street."

“We think he'll make a great police officer."