Staff at the steel and glass building overlooking the Thames have said that mice currently have the run of City Hall

One source said workers “can’t leave food out - even locked in drawers, as the mice get at it”.

And if Number 10 Downing Street, the Foreign Office cat, the Treasury and the Cabinet Office have all adopted cats to chase down mice, then why not the Mayor’s own domain?

Mr Copley told The Telegraph: “There is a serious problem with mice at City Hall. One fell out of the ceiling in front of a group of school children quite recently. You can't leave food out anywhere.”

“The solution to this would be to get one or more cats.Support for the cat would come down more to like or dislike of cats rather than party allegiance.