You probably don't remember knocking on our door 18 months ago. You and your colleague in your big riot van early one Friday evening in March. I can still remember the shock of having an officer standing in the doorway telling me you had my son sitting in the back of the van and could you come in.

I was in end of the working week mode, you could probably tell. Silly apron on, glass of wine in hand, fresh from eating a takeaway tea. All was well in our world and, frankly, I would have been less surprised if ET had knocked on our door.

We listened with mounting trepidation as you explained that our son K had been picked up after he had run off when he and a friend had seen your van.

You had been on the lookout for car thieves and were suspicious when the two teenagers sprinted away. The reason for their flight was clear when they were stopped. In their possession was a half empty bag of cannabis. Both of them as high as kites about to, in your words "chuck a whitey".

You had a range of options. In those few minutes you had the power to seriously affect our son's life. You must have been in a similar position many times. Thankfully, you decided to return him to us with a warning. You didn't judge us or pass any comment about our parenting. Perhaps you could see or sense the shame and guilt radiating off us, the normality of our Friday evening kicked away from underneath us.

You simply gave us answers to a series of questions that I imagine you must have asked dozens of times at secondary schools to teachers and concerned parents. Did we know what cannabis smelt like, looked like? Did we know how to tell if someone was "under the influence"? Were we aware of the penalties for possession? Did we need information about who to contact if we needed help and advice?

Your colleague then brought our son to the door, explaining that he was worried about our reaction.

White faced, pupils dilated, he slunk upstairs to the bathroom where we could hear him being violently sick. You gave us your name and badge number, told us to get in touch if we wanted K spoken to further. We said we would deal with it.

K has moderated his risk-taking behaviour. Two years on he is still growing and learning, getting things right and occasionally getting things wrong. Because of your empathy, understanding and ability to exercise discretion he has a chance grow up without a serious mark against him on his record. Your treatment of him has helped him form positive views of the police. He knows the risks he ran and how the consequences could have affected him.

Our son recently applied for and got a job with a national retailer. He applied for and now has a place at university. We talked about what happened that Friday as he filled in the forms for these life-changing events. A light-bulb moment for him.

As the years go on, I am sure he will appreciate your actions that night more and more. I doubt, however, that his appreciation will ever be as great as ours. Once again, thank you.

Anonymous