English "Teacher"
Around the time I was in year 10, a new English teacher arrived (the old one had probably had a nervous breakdown; that happened a lot at our school). Whilst I was never taught by him, many of my friends were. He was a very large, jocular-looking man who insisted that his classes call him by his first name, Dennis, rather than "sir".

He was also a rather bad teacher. There was a reason for it, as we found out the day the police came to the school, and, as quietly as possible, arrested him.

It turned out that his name was not, in fact, Dennis, and he was not, in fact, a teacher. He was, I believe, charged and convicted with fraud. My old form tutor (a top bloke) says that he was actually impersonating a real teacher named Dennis, which is how he got in in the first place. Of course, he managed to throw a decent spanner in the works of about a quarter of the years' English GCSE's (he was there for about a year before he got busted). I don't think anyone was entirely sure what his motives were for impersonating a teacher specifically. My friend and I always assumed the worst when we made jokes about him.
(Frank Snow, Wed 16 Nov 2005, 0:52, Reply)