I met my worst parent on a trip to the Imperial War Museum. We needed parent volunteers, but let's just say this chap turned out not to be as good as a conscript; a deserter might have been more use.
He had served in the Territorial Army and was clearly a military obsessive. On the coach, he gave me an excruciatingly dull account of the Normandy landings.
He showed no interest in the kids - including his own - and as soon as we arrived he shot off to the exhibits that interested him.
Thankfully, we lost track of him during the day. The visit was superb and we certainly didn't miss our own Colonel Blimp.
He checked in with us at lunchtime, only to criticise some of the displays and staff for alleged historical inaccuracies. He also took a loud and offensive dislike to a charming party of Japanese youngsters. His son looked for a fox hole in which to hide.
Then he disappeared again, presumably for further reconnaissance behind enemy lines. At the end of the day, the group was one short. We sent out a search party and found our hero arguing with a member of staff in the shop.
I grabbed a colleague to sit next to on the return journey. As I got off the coach - an hour late - to face the miffed parents, our friend offered his "expertise" for future trips. I politely declined, but couldn't resist giving him a sly V-for-victory send off as he retreated.
The writer teaches in a Kent primary school.