Evie is named after Dame Evelyn Sharp, the first female permanent secretary.

Two rescue cats have joined the UK government's rapidly expanding team of mousers, bringing the total number of official parliament cats to five.

Evie and Ossie came from the Celia Hammond Trust and now have the run of four floors at the Whitehall office.

The Cabinet Office announced the pair's arrival on Twitter: 'Welcome to our new cats Evie & Ossie, rescued by @CeliaHammond. Arrived in time to celebrate our 100th birthday & catch some mice! #CO100'

Evie is reportedly named after Dame Evelyn Sharp, the first female permanent secretary, while Ossie takes his name from Sir Edward Osmotherly, who authored the rules for civil servants giving evidence to select committees.

Ossie takes his name from Sir Edward Osmotherly, who authored the rules for civil servants giving evidence to select committees.

The pair join three other parliamentary felines, all of whom are looked after with staff donations. Downing Street cat Larry was given the task of eradicating mice from No 10 in 2011, while Palmerston was recruited to the Foreign Office in April, and Gladstone moved into the Treasury in July.

Larry and Palmerston have been in the throes of a well-publicised feud for months, resulting in the pair being kept apart after a series of major public spats.

According to recent media reports, Chancellor of the Exchequer Phillip Hammond has been forced to keep his dogs out of Larry's 'domain' to avoid clashes since moving into No 10.

Images courtesy of the Cabinet Office