I am mad. Absolutely barking. We are not talking your average "that Titanic was a really great movie, I must go and see it again" type madness here. More your full-on "stick two pencils up your nose, put your Y-fronts on your head and say 'wibble'" variety. How do I know this? Because everybody keeps telling me.
The first person to let it slip was the senior partner of my old firm, Mr Rann. After spending three years training as an agricultural accountant, counting sheep, pigs and wheat, I decided that a change was needed. The blackboard and chalk called. So I went to see him.
"Mr Rann, I'm handing in my notice. I want to be a teacher."
"You do know that you are earning as much now as you will ever earn as a teacher?" "Yes, I know."
"And you still want to teach?" "Yes."
My head of department was next. Her suspicions were aroused when she noticed that I never stop smiling. Still, being a tolerant sort she was willing to give me the benefit of the doubt, until Year 7 parents' evening. Halfway through, she walked over to my table.
"So, what do you think of parents' evenings?" she asked.
"They're smashing fun, aren't they," I replied, grinning from ear to ear.
I was starting to get worried. Still there was always the pupils. Surely they must see me as a rational human being? No. They question my sanity on two fronts. First, my dress sense. The dark suits, blue blazers and chinos are OK. They can even cope with my choice of three pink shirts (all with matching cufflinks). But when I wear my tweed jacket and sleeveless cricket sweater, calf-length wax coat and tweed flat cap, they lose it.
"Sir, you look like an extra from Emmerdale."
"Thank you, Tracey. It's a great combination, don't you think?" "You're mad."
But my dress sense isn't my only sign of insanity. There is also the case of my singing. I sing everywhere. I blame my father. Every morning about sixish, he and I used to take the dogs for a walk. As we set off we would burst into song - usually that drinking song Kurt Juergens gets his U-boat crew to sing in The Enemy Below.
My Year 10 especially don't seem to appreciate my music. They have noticed that every Thursday morning, while they are writing about the American West, I walk around the classroom singing Robbie Williams's "Angels" to myself. This is always the last song played in the club I work in on Wednesday nights, but I don't believe that the pupils need to know this.
"Sir, you're singing 'Angels' again!" "I find it relaxing."
"You're mad, Sir."
My last hope was a group of old friends. So I popped up to London to see them. Like most of the people I know well, they have trodden the same path from public school, to university, to the City. My becoming a teacher is, therefore, a bit of a novelty. They were all keen to find out how my time was going at a "challenging" comprehensive. Is it like Grange Hill? Are there many fights? Do all the teachers read The Guardian?
"Still," one of my oldest friends asked me, "after this year, you'll be looking for a job in a boarding school, won't you?" "I'm actually enjoying teaching where I am, so I hope to find a job in a similar type of school."
"You're kidding?" "No, it really is superb fun."
"You're mad!" And that, as they say, is that. When even my oldest friend thinks I'm two sandwiches short of a picnic, it is time to stop pretending. I must now head off into town. Year 8 are studying 19th-century France and I need to hire a Napoleon costume.
They ain't seen nothing yet.
Nick Lind is a secondary PGCE student in history at Bristol University