Ofsted. Welcomed into schools like a snot and vomit virus.
It was always fun trying to match up to whatever was the Unswerving Orthodoxy in teaching practice at that particular time. In general, new Unswerving Orthodoxies came around on a three year cycle. The pupil's white board, for instance, to be used in interactive starter activities at the beginning of lessons. Firstly starter activities were mandatory, then they were strongly recommended, then they were abandoned, and there were store cupboards full of piles of whiteboards.
The whiteboard was interesting but fabulously impractical. And, being double-sided, meant that you could show the teacher the correct spelling of "receive" and the pupil behind you "cock", complete with a bus stop penis. I would have, anyway.
In ten years I was only visited once, which I was not overly upset about because I hated being observed. It was a Key Skills lesson and out of the two disaffected sixth formers in my class one was skiving. So when the inspector walked in I was sitting at the computer with an autistic kid slowly devising a customer service questionnaire for him to use in his Business Studies. We did it for forty minutes and the inspector sat and watched. I hope he was impressed, but I never found out.