Foreign Office mouser Palmerston is retiring after several months "working from home" during the coronavirus crisis.
The rescue cat, who joined the department in 2016 to control pests, has been cared for by an FCO staffer during the pandemic.
A "resignation letter" published on the feline's official Twitter account said the much-beloved animal, known affectionately as DiploMog, had found life away from the Foreign Office's King Charles Street headquarters "more relaxed, quieter, and easier".
Last year Palmerston took a leave of absence after he was found to be over grooming – a sign of distress in cats.
On his return to Whitehall in December, FCO permanent secretary Sir Simon McDonald issued staff with a set of rules to minimise his stress. The so-called Palmerston protocols reduced the size of Palmerston's mousing territory and instructed staff to give him “full choice and control of who he deigns to greet or imperiously ignores”.
Palmerston's resignation letter said: "I have enjoyed climbing trees and patrolling the fields around my new home in the countryside."
"Of course I love the hustle and bustle of the office. I will miss hearing the footsteps of an ambassador and sprinting to my hideout to see who it is. My signature move: pretending to be asleep while overhearing all the foreign dignitaries' conversations, will be a major loss for our intelligence gathering," he added.
"But as I grow older, I must take a step back from my diplomatic duties and enjoy some me-time."
Sending his best wishes to the retiring moggy, Mcdonald – who announced his own retirement last month – said "everyone @foreignoffice will miss him".
Palmerston leaves behind his No.10 rival Larry, Treasury mascot Gladstone and Cabinet Office mother and son duo Evie and Ossie. Evie, who was adopted from the Celia Hammond Animal Trust in 2016, was promoted in April to become the face of the Government Equalities Office.