David and Samantha Cameron announced the birth of their fourth child today - a baby girl born three weeks early.
The Prime Minister's wife was driven to hospital this morning after experiencing contractions over the past two days, a day after she posed for photographers on holiday in Cornwall.
The baby 'popped out' at about midday after being delivered by Caesarean section at the Royal Cornwall Hospital in Truro.
The baby weighed 6lb 1oz. She had been due next month but arrived early while they were holidaying in Cornwall.
Speaking outside the hospital today, Mr Cameron, who was present at the birth, said it was 'absolutely thrilling, really exciting', adding: 'It all happened very quickly. It was a bit of a shock to have the baby here in Cornwall.
'My job was to make the toast and tea.'
Praising staff at the hospital, Mr Cameron called the nurses 'wonderful' adding that they had 'put us at our ease' during the birth.
The Prime Minister added that he was 'getting the baby names' book out' and it was likely the couple would choose something of a Cornish origin.
The Camerons' daughter is only the third child born to a serving prime minister since 1849.
Tony and Cherie Blair's son Leo was born in 2000.
Downing Street said both the baby and Mrs Cameron were 'doing very well'.
The Camerons' eldest son Ivan, who suffered from cerebral palsy and severe epilepsy throughout his life, died aged six last January.
Their two other children are six-year-old Nancy and Arthur Elwen, four.
Mr Cameron is expected to take two weeks' paternity leave.
So what do you think the Camerons will call their daughter?
Have a look at our baby names section for inspiration.
My bet is on Tamsin - a good Cornish name.
Read the latest Cameron baby name news.