A third cat has joined Whitehall's team of mousers with the arrival of Gladstone at the Treasury.
Like Larry the Downing Street cat and Palmerston of the Foreign Office, the black cat is a former stray adopted from Battersea Cats and Dogs Home.
Amid mounting speculation that Larry and Palmerston are engaged in a turf war, Gladstone's official Instagram page describes him as an animal with "catitude".
And the 18-month-old domestic short-hair wasted no time in getting involved in the apparent spat.
Named after former prime minister and chancellor William Ewart Gladstone, his profile also describes him as "the most popular colleague at Her Majesty's Treasury", where he catches mice and "receives cuddles".
After a recent "fracas" with Palmerston, Larry had to be treated by a vet after developing a limp in his front right paw.
It was unclear whether Palmerston was responsible but the Foreign Office's "diplomog" has been pictured in recent days being evicted from No 10 and squaring up to Larry.