A cat named Larry is in charge of pest control at 10 Downing Street

The official title of Chief Mouser to the Cabinet Office is held by a cat in charge of keeping mice under control at the UK Prime Minister's residence and office at 10 Downing Street. The current incumbent is Larry.

Larry the cat, Downing Street's Chief Mouser since 2011
Larry the cat, Downing Street's Chief Mouser since 2011

It was once commonplace to employ cats as mousers, so there have been other opportunties for cats like the UK Post Office's Tibs the Great to rise to prominance.