You might think someone who earns the dubious title of “worst parent” might not be fit to be called parent. But in this case he was simply too fit - and that became my problem.

I was a deputy head and the only running I did was to run myself into the ground with work. So, like many, when I was inspired by the tales of heroism of those running the London marathon, I promised myself I would run the following year.

I joined a gym, cycled to work and wobbled a few miles on a Sunday run. I was making progress, but not enough. So I put pressure on myself by announcing my ambitions to the whole school, and I got a sponsored place with a high-profile charity.

Enter Mr Motivator - a super-fit parent who decided to make me his project. Not only would I complete the marathon, but I would do so in less than three and a half hours. All I had to do was submit to his training regime.

This I did and the sponsorship pledges swelled. I was hitting the pavements every night in all weathers.

At first, I tried to run through the pain in my hip. My “coach” told me it was just my body adjusting to the workload. Like a fool I listened. And I kept listening right up until the moment I collapsed at the end of a 25-mile training run. I ended up in hospital with a stress fracture in my lower back.

But at least I was able to watch the marathon with my feet up. The parent did the run in my place, dipped below three hours 15 minutes, raised all the money that I was pledged, and was treated like a hero. I don’t think I have ever hated a human being as much, before or since.

The writer is a deputy head. Send your worst parent stories to features@tes.co.uk. Those published will receive #163;50 in MS vouchers.