Mew Labour is dead. Sybil, who was the first cat to take up residence in Downing Street in 10 years, has died after a short illness.

Sybil belonged to Maggie Darling, who introduced her to 11 Downing Street when her husband, Alistair, was appointed Chancellor two years ago.

Her arrival in Downing Street was announced in an on-the-record briefing to journalists by the Prime Minister's official spokesman in September 2007. He said: "Mr and Mrs Darling are living in the flat above Number 10. I understand they do have a cat and the cat has recently been brought to Downing Street."

Asked whether Sybil would have the run of the house and gardens, he added: "It's quite difficult to confine cats, so, yes. The Prime Minister doesn't have a problem with it. Sarah Brown doesn't have a problem with it."

In that same week, the Northern Rock building society crashed, and hundreds of anxious investors queued in the streets for their money, in a prelude to the banking crisis that would plunge the world into recession.

No doubt the arrival of a black-and-white puss added an element of serenity during a mad and stressful period in the Chancellor's career, but life at the top did not altogether suit Sybil, who was named after the hostess in Fawlty Towers. She seemed unhappy, and last February Maggie Darling took her back to Scotland, where she died.

Having Sybil wandering about the Downing Street gardens, or finding her way through from No 11 to No 10, will not necessarily have been welcomed by the neighbours.

Gordon Brown is reputed not to be a great animal lover. It is even rumoured that he had an aversion to dogs, and that when he visited the USA, Eddie, the elderly dog belonging to Sir Nigel Sheinwald, British Ambassador to Washington, had to be confined to his kennel to prevent him trying to make friends with the Prime Minister. This is denied by the Foreign Office, and Downing Street's official line is that Mr Brown likes dogs.

His two young sons are certainly showing early signs that they will grow up to be fond of pets – Mrs Brown revealed on Twitter that the appearance on television of Barack Obama's pedigree Portuguese water dog (named Bo after the President's initials) had given five-year-old John Brown and three-year-old Fraser ideas.

"Pets?" Mrs Brown wrote. "Do you have any idea the trouble that a dog called Bo has caused me? The new pet campaign has started." She later added: "I fear the subject of pets will continue for some time."

Downing Street was a pet-free zone for almost a decade until Sybil arrived. Before that, there was Humphrey the Downing Street cat, a stray who wandered in while Margaret Thatcher was Prime Minister, in 1989, and remained throughout John Major's premiership.

Humphrey the cat was even included on the government payroll, receiving £100 a year from the Cabinet office budget, unlike Sybil, who received no public money.

Humphrey disappeared in November 1997, six months after Tony and Cherie Blair moved in. Dark rumours circulated that Mrs Blair had him put down because she thought cats were unhygienic, even leading to a question in the House of Commons from a Tory MP. Alastair Campbell arranged a photocall to show that Humphrey was alive and well, in a new home. He died in 2006.