Introducing Sybil, Downing Street's first cat for a decade

In the latest break with the Blair era, a cat is back in residence at Downing Street for the first time in a decade. The job of official mouser has gone to Sybil, a black and white cat owned by the Chancellor, Alistair Darling, and his wife, Margaret.

She follows in the famous paw-steps of Humphrey, who served Margaret Thatcher and John Major before being mysteriously "retired" in 1997 amid rumours that Cherie Blair was allergic to cats.

The Darlings have brought Sybil, named after the character played by Prunella Scales in Fawlty Towers, from their Edinburgh home to live in their flat above 10 Downing Street. It is understood that the Darlings will be footing the bill for the Government's newest recruit.

Sybil will be given privileged access to the heart of government to help fulfil her task of keeping the building free of vermin.

Gordon Brown's spokesman explained: "It's quite difficult to confine cats. The Prime Minister doesn't have a problem with it. Sarah Brown doesn't have a problem with it."

Until the Blairs arrived in Downing Street, there had been a long tradition of cats prowling the residence. Wilberforce took office alongside Edward Heath in 1970 and went on to serve under Harold Wilson, James Callaghan and Margaret Thatcher.

He was succeeded by Humphrey, a long-haired black and white stray named after Sir Humphrey Appleby, the Machiavellian civil servant in another TV sitcom, Yes, Minister.

Humphrey had a controversial record, surviving only after winning Mr Major's backing in 1994 when he was blamed for the death of four robin chicks nesting outside the Prime Minister's office.

The following year he went missing, presumed dead, but returned to Downing Street after staff at a Westminster medical college read his obituary and realised their new moggy was the Government's official mouser.

Within a week of the Blairs moving in, reports emerged that Humphrey had fallen foul of his new mistress – claims she strenuously denied.

Sensing a PR disaster brewing, and with angry letters beginning to arrive from cat lovers, Alastair Campbell, Mr Blair's press secretary, rapidly arranged a photo call, with Cherie and Humphrey pretending they were the best of friends.

The rumour mill started again in November 1997 when No 10 announced that Humphrey had gone into retirement with an elderly couple in south London. On the Blairs' orders, photographers were taken to picture him posing with that day's newspapers to scotch speculation that he had been put down.

Whitehall files later disclosed he had been pensioned off – with his food and vet bills paid from a £100 annual Cabinet Office stipend – because he was no longer up to the job of chasing mice.

Although Mrs Blair was cleared of blame for his removal from high office, a replacement was not made until the new boss moved into Downing Street.