Parents fall into one of three categories: those who don't care; those who take the whole school thing seriously but not too seriously; and those who get just about everything out of proportion.
While it is the first category that most heavily swells the ranks of problem parents, it is the last lot that give can give you nightmares. And so it was with my worst parent.
Not only was she in the "pure zealot" category, she was also - and it hurts me to say this - a fellow teacher. This was truly a double whammy: not only was she difficult and demanding, but she had an insider's perspective. You would think that this would make someone more sympathetic, but it doesn't always work out like this. After all, the best gamekeepers are often the best poachers.
So here was someone whose daughter had not got into their first choice of school; an insider who had failed to play the system (despite conducting more appeals than Ronnie Biggs). She came with, as they say, "an agenda". And one dripping with vitriol.
It could have been worse, I guess. She could have been an Ofsted inspector. But then again, I don't know whether anyone could have subjected my methods to more rigorous and hyper-critical scrutiny. Here was someone with a point to prove, who probably subjected her poor kid to a minute-by-minute cross examination into the minutiae of my every lesson.
It didn't help that this fellow professional saw herself (and her school) as the embodiment of excellence (which was not the case). Everything I did was benchmarked against unrealistic expectations.
If this tale were a TV drama, I would have won her round and it would have ended with smiles and a handshake. As it was, after a whole year of this, I would have happily strangled the bitch.
The writer is a teacher in south-east London. Send your worst parent stories to firstname.lastname@example.org and you could earn #163;50 in MS vouchers.