Britain's ultra-wealthy new British prime minister Rishi Sunak and his family plan to live in the flat above number 10 Downing Street, despite owning a string of luxury properties including one in London.

Sunak's portfolio of properties reportedly includes a penthouse in California, an apartment in London's exclusive Kensington district and a mansion in his Yorkshire constituency in the north of England.

But the prime minister's secretary has confirmed he will be moving into Downing Street.

"They will be moving into the No 10 flat," the spokeswoman said, adding that she did not know if they had any plans to redecorate.

Johnson got into hot water over an expensive refit of his prime ministerial flat.

The ousted premier's lavish refurbishment of his flat, next door at No 11 Downing Street, was overseen by his wife Carrie. Controversy over the way it was funded handed ample ammunition to Johnson's critics.

The details of expensive rolls of wallpaper, hyper-fashionable soft furnishings and deep-pocketed donors became the stuff of endless newspaper articles that ultimately undermined his authority.

Although the No 10 flat in Downing Street is in a prime location, it is relatively small.

Sunak's move there will mark a return the flat being the London home of the British prime minister.

- Sunak's Labrador comes too -

Traditionally British leaders lived in the flat above number 10 Downing Street. The main building it sits above is the official residence and office of the country's prime ministers.

Chancellors generally lived in the larger flat above No 11.

However when Tony Blair and Gordon Brown were prime minister and chancellor, they swapped flats to accommodate Blair's growing family.

In fact, Sunak only recently moved out of No 10 flat as he lived there during his time as Johnson's finance minister, until resigning in July.

Asked why he had chosen to live at No 10 and not the bigger No 11 flat, the spokeswoman said: "They were very happy there."

The Sunaks, who have two daughters and a Labrador dog, however, are unlikely to need to rely on rich backers for any flat redecorations.

Before marrying the daughter of an Indian billionaire in 2009, Sunak worked at Goldman Sachs investment management company and two hedge funds,

His wife Akshata Murty owns a substantial stake in her father's Infosys software company.

Together, the couple are on The Sunday Times rich list, with a net worth of 730 million pounds.

British prime ministers also have the use of a country residence, Chequers.