I had excluded - let’s call him Darren - several times, including for possession of a gun. He must have been 14 or 15 and he had very pleasant parents, not aggressive at all. They came to see me after the final, permanent exclusion. It must have been 20 years ago, but I remember it as if it was yesterday.

At the end of the discussion they left my office - mum first, then Darren and finally the dad. Just as the father reached the door, he turned to me and said: “I don’t know what’s the matter with Darren. He’s always had everything he’s ever wanted.”

To me, that said it all. They were baffled rather than angry. They just could not understand how such an approach could fail.

When Darren turned 16 he pestered them for a motorbike, I heard. They said they would only give him one if he behaved. But his behaviour didn’t improve, so they bought him one anyway saying now that he had it, his behaviour had to improve in future.

It didn’t, of course. I think he ended up in prison. It was a classic case of terrible parenting. Materially he had everything, but he never had any boundaries.

I would regularly cite this story as a cautionary tale for the parents of our incoming Year 7s. I told them that if they brought up their youngsters as free-range children the school would inevitably fall out with them. There would be too much tension between how things were done at school and how they were done at home.

It hammered the message home. At least I can thank Darren’s parents for that.

- John Dunford is a former general secretary of the Association of School and College Leaders. He was headteacher of Durham Johnston Comprehensive School. Send your worst parent stories to features@tes.co.uk and you could earn #163;50 in MS vouchers.