There has been a Chief Mouser of the Cabinet Office for near 100 years now, the first official one being Peter (one of several Peters to hold the job officially). Peter was the first to be formally appointed the title and to have an allowance from the Exchequer for his upkeep (a penny a day if memory of the story serves).

I'm especially pleased that one of the line was a Manx, her name was Peta (the feminine of Peter in honour of her predecessors).

It is, like many things, a long tradition quietly held.