Cameron's Big Society grows by one

(GETTY IMAGES)

It was one job that Nick Clegg could not deputise for. In one of the more surprising interruptions to a family holiday, David Cameron was at his wife's side in a Cornish hospital last night after she gave birth to the couple's fourth child yesterday.

Samantha Cameron, who is 39, had contractions in the morning. She and the Prime Minister went to the Royal Cornwall Hospital in Truro, where their 6lb 1oz daughter was delivered by Caesarean section at midday.

The baby had not been due for another fortnight and the Camerons decided to go ahead with their summer break even though they knew it could arrive at any time. Friends said there were no complications and no emergency. The couple's other children were delivered by Caesarean section after complications at the birth of their eldest, Ivan, who had celebral palsy and severe epilepsy, and died aged six last year. Mr Cameron spoke of their hopes of having another child after Ivan's death.

It is normal practice for a mother who has had one Caesarean to have her other children delivered in the same way. The Camerons' other children are Nancy, six, and Arthur Elwen, who is four.

Their new arrival is the third born to a serving prime minister since 1849, when Francis Albert Rollo Russell, son of Lord Russell, was welcomed to No 10. The second was Leo Blair, in 2000.

A beaming Mr Cameron, 43, told reporters outside the hospital that mother and baby were doing very well. Although his "unbelievably beautiful girl" did not have a name yet, he said it would "have to have something Cornish in the middle".

"It was a bit of a shock," he conceded. "I always thought it was possible because Samantha's have tended to come a bit early and she'd been having contractions for the last couple of days on and off and just thought this was time to come to the hospital and check out to see if everything was fine and the next thing we knew they were all getting into the gear and the baby was coming out."

Mr Cameron will take paternity leave but has not finalised it yet. He may take some time off next week, and return to work fully the following week, when the House of Commons returns from its summer recess. He could take the second part of his paternity leave during the party conference season, when the Commons does not sit.

Nick Clegg, the Deputy Prime Minister, already "holding the fort" during Mr Cameron's holiday, may have an extended spell in the role. Despite the early arrival of the Camerons' baby, Mr Clegg will still represent the Government at a United Nations conference on global poverty in New York next month, even though it overlaps with the Lib Dem conference in Liverpool.

The Camerons, who had been reluctant to leave their Notting Hill home, were persuaded to move to Downing Street after the election on the advice of security experts. They are currently living in the cramped flat above No 10 while the larger flat above No 11 is being renovated. George Osborne, the Chancellor, and his wife, Frances, who have two children, have decided to remain at their Notting Hill home rather than move to Downing Street.