LONDON — When Palmerston, the U.K. Foreign Office’s “chief mouser,” vanished from public view earlier this year, some became concerned about the black-and-white rescue cat's whereabouts.

But now the creature's @DiploMog Twitter profile, which has 100,000 followers, has announced his return to frontline duties.

Like countless human office workers, Palmerston needed time off because he was suffering with stress, Sir Simon McDonald, the permanent under secretary and head of the Diplomatic Service at the Foreign Office, said on Monday.

“It was no longer an environment that was working for him,” he wrote in a internal blog to staff. “He was over-grooming on his front legs, a sign of stress.”

Palmerston, named after Britain’s longest-serving foreign secretary, was moved on vet's advice to the home of one of McDonald's staff in July. He is one of a number of cats connected to British government departments with popular social media presences — a trend that began with Larry the Cat, which works at the home of Britain’s prime minister, Number 10 Downing Street.

“During his summer holiday, Cabinet ministers, colleagues and overseas visitors have asked me anxiously about his whereabouts,” McDonald wrote. “The good news is that Palmerston is coming back this week. But we must remember why he needed a break, and change our behavior towards him.

“He is happy, healthy and full of energy. His pelt is glossy and mostly grown back. We need now to keep him that way.”

The @DiploMog Twitter feed set out new rules for Foreign Office staff when the animal returns to active duty.

Dubbed the “Palmerston Protocols,” the posts said they were “designed to ensure my welfare and happiness.”

I am happy to announce that I will be returning to my Chief Mouser duties at the @foreignoffice this week! New guidance - the Palmerston Protocols - will govern my care in the FCO to make sure it’s working for me. (1/4) pic.twitter.com/j2AFKI0DGN — Palmerston (@DiploMog) December 2, 2019

They added that the Foreign Office was housed in a “very big, old building and I was finding it difficult to maintain a territory so large."

The new zone "is much more manageable, and has lots of comfy seats for naps," the feed said.

Elaborating on this McDonald wrote in his blog: “Cats are territorial. They fret when their territory is bigger than they can manage.”

He said that in the zone, Palmerston "should be allowed to choose whether he wanted to interact with staff."

He added: “Don’t wake him if he is sleeping. He has full choice and control of who he deigns to greet or imperiously ignores.”

Twitter feeds dedicated to other cats belonging to government departments welcomed Palmerston back.

Larry the Cat, tweeted: “All I want for Christmas is you!”

Humans also tweeted their greetings.

One @PixieSteven wrote: “Welcome back Sir, just in time for Christmas pawty x.”

Another TheSaltySeaCat added: “Best news of the day! Could you add one more protocol that makes politicians stop slinging mud at one another. We are only interested in pawlicies.”