I used to get the letters because I bought a TV for use as a monitor for video projects and I was stupid enough to give my address when asked to.

They're sent out on a cycle with a bit of randomness. It's quite fun to collect the set.

They stopped when I phoned the Bristol office and they asked how I'd feel if an inspector came over. I told them they were welcome any time, and the drive over would be a nice day out. [True]