Recently, I went on a walkabout with some police officers and children from a Carlton primary school.

The police wore high visibility jackets. The children and I had high visibility tabards. We could scarcely be missed as we walked down the street.

One of the children was carrying a speed gun – and that was the point of what we were doing. The children had been learning about how they needed to take great care when crossing busy roads and how far a car will travel even after the breaks have been applied.

We stopped on a main road just a short distance from the children’s school.

The children then took it in turns to record the speed of approaching motorists. It was a 30mph zone.

Anyone driving at over 35mph was clocked on the speed gun and a police officer pulled them over.

Some were way over the speed limit even though they had tried to slow down when they saw the yellow jackets. Most were women.

The officer explained to the motorist that they were lucky. If the speed gun had been in the hands of a police officer, it would have meant fines and possibly points. But this was an educational exercise conducted with the help of the children.

Then a couple of the children were invited to talk to the motorist about his or her driving.

They gave some facts about speeding and its dangers.

But one nine year old girl asked some questions that were quite hard for the motorist to hear.

‘Do you know how far you would have travelled after you put the brakes on?’

‘If I’d been crossing the road, can you imagine the sort of injuries I would have if you couldn’t stop in time?’

‘What would you say to my mum if you had hit me?’

The motorist struggled to continue looking the girl in the eye. His passenger went pale and tearful.

We are probably all guilty of speeding. Yet every holiday period seems to bring its sad toll of road traffic collisions, many caused by driving too fast.

Traditional means of reducing speed have some effect – traffic calming measures being more effective than speed limits.

But sometimes we need something more to bring it home.

As well as 20mph signs, perhaps we also need an image of a nine year old girl in a high visibility jacket looking directly at us, a speed gun in her hand.