Larry the cat joins David Cameron in Downing Street

David Cameron has welcomed a cat to Downing Street in an effort to deal with No 10's rat problem.

The four-year old tabby, called Larry, was at London's Battersea Dogs and Cats Home before moving in to the UK Prime Minister's home.

The arrival follows weeks of speculation about potential pest control measures after a large black rat was seen scuttling past No 10.

A Downing Street spokesman said the former stray was a "good ratter".

Larry arrived via van shortly after 1300 GMT, and was carried into Number 10 in a covered cage.

According to Downing Street, the animal has "a high chase-drive and hunting instinct", developed during his time on the streets.

A spokesman said he had also shown "a very strong predatory drive" and enjoyed playing with toy mice.

In a statement Mr Cameron said: "I'm delighted to welcome Larry to his new home.

"He came highly recommended to me by Battersea Dogs and Cats Home, who did a fantastic job looking after him.

"I'm sure he will be a great addition to Downing Street and will charm our many visitors."

And the PM's official spokesman later reported Larry had slept through most of his first afternoon in Westminster, saying he "seems relaxed and easy going".

But the animal appeared to bely his reputation as gentle when he scratched reporters from ITV News and Sky News who tried to hold him as part of their reports.

Larry arrived in a cat basket which was covered as he was carried past the waiting press pack

Given his exalted status among the nation's pest controllers, Larry's name is appropriately a shortened version of Lawrence, meaning "laurel-crowned".

He is the latest in a long line of Downing Street cats, known unofficially as Chief Mouser to the Cabinet Office.

Humphrey was adopted in 1989 after wandering into No 10 as a stray while Margaret Thatcher was prime minister, and remained throughout the administration of John Major.

He moved out six months after Labour's 1997 general election win, with Tony Blair's wife Cherie denying reports that her dislike for the animal was to blame.

Humphrey died in March 2006 at the home of a civil servant who had cared for him during his "retirement".

The last feline to live in Downing Street was former Chancellor Alistair Darling's cat Sybil. She reportedly did not adapt well to life in central London and moved to Mr Darling's Scottish residence.

During the 1920s, Labour Prime Minister Ramsay MacDonald's cat - a renowned rat-catcher - had the rather regal title of Rufus of England, but was nicknamed "Treasury Bill".

Another, the topically named Munich Mouser, is mentioned as being "in office" under Neville Chamberlain and Winston Churchill during the 1930s and early 1940s.

During Tory Edward Heath's premiership in the 1970s, a kitten called Wilberforce was acquired from the RSPCA. He retired in 1986, with Margaret Thatcher reported to have bought him a tin of sardines during a trip to Moscow.