What Does the Chief Mouser Actually Do?

June 24, 2026

What Does the Chief Mouser Actually Do?

From Rufus of England to Larry the Cat, the surprisingly long history of Britain's Chief Mouser to the Cabinet Office.

When Britain's Prime Minister changes, one resident of 10 Downing Street usually stays put. His name is Larry, and whenever political upheaval hits Westminster, headlines inevitably point out the same thing: Larry the Cat has outlasted another Prime Minister. But behind the jokes is a surprisingly old job.

The title "Chief Mouser to the Cabinet Office" sounds ceremonial, but it exists for a practical reason. For centuries, buildings that stored food, paper records, and supplies had a common problem: mice. So you got a cat, that's the simplest solution.

For a very long time, ships had ship's cats, distilleries employed mousers, warehouses, shops, and bodegas often relied on resident felines long before modern pest control existed. And government buildings were no exception.

The first recorded cat employed at Number 10 was Rufus of England, also known as Treasury Bill, who arrived in 1929. Historical records show that the Treasury officially funded cats to control rats and mice at the Prime Minister's residence. Rufus received a weekly allowance for his services.

Many Chief Mousers followed, including Peter, Bob the Munich Mouser, Nelson, Peta, and Humphrey. Some of them even became celebrities and made tabloid headlines, while others got on with the job. All of them together became part of a civil service tradition that has survived economic crises, world wars, elections, and more than a century of political change.

Larry arrived in 2011 from Battersea Dogs and Cats Home and remains the most famous holder of the position. His job description is pretty much the same as his predecessors': patrol the grounds, discourage rodents, and serve as the unofficial face of Downing Street whenever the public needs a break from politics.

Larry does not receive an official allowance like some earlier Chief Mousers. As he told us in an interview, his food and vet bills are covered by staff at Number 10. "I don't cost the taxpayers a penny," he said.

Of course, the role has always been about more than catching mice.

Working cats often become part of the communities they serve. Towser guarded a Scottish distillery and earned a Guinness World Record as the World’s Greatest Mouser. During wartime, countless ship's cats like Simon and Herman lived alongside sailors and servicemen. They were mousers, companions, and morale officers.

The Chief Mouser occupies a similar place in British public life. Prime Ministers come and go, elections reshape governments, but through it all, there is usually a cat somewhere behind the famous black door at Number 10, carrying on one of Britain's oldest and most unexpectedly enduring jobs.