Sir Paul McCartney and Heather Mills said today they were "ecstatic" after becoming parents of a baby girl called Beatrice.
The youngster was born on Tuesday at a north London hospital close to their home in St John's Wood. News of the birth was kept secret until today.
The youngster weighed in at 7lbs.
A statement issued by the couple said: "Heather and Paul McCartney are delighted to announce the birth of their baby daughter Beatrice Milly McCartney who was born in London on 28 October at 8.45pm by Caesarean section.
"The baby who arrived three weeks early weighed in at a healthy 7lbs and both she and mum are doing well.
Sir Paul, who is 61, and 35-year-old Heather said: "She is a little beauty and we couldn't be prouder."
She is named after Heather's mother Beatrice and Paul's auntie Milly.
Sir Paul has three children from his marriage to Linda, who died in 1998 - musician James, 25, photographer Mary, 33, and fashion designer Stella, 31. He also has a stepdaughter, Heather, from Linda's first marriage.
Beatrice was delivered at the Hospital of St John and St Elizabeth in north London, close to Abbey Road where The Beatles recorded most of their magical moments.
Heather's delighted father Mark, 62, told of his joy today and hoped the delivery of his first grandchild would help build bridges with his estranged daughter.
Mr Mills, who has suffered a stroke, said he hoped to see the baby soon, and added: "I am very proud of my daughter and what she has achieved."
Speaking from his flat on the outskirts of Washington, Tyne and Wear, he said: "This is my first one and it is a grand time for me and I love the new baby. I sincerely hope the baby will bring us together again."Reuse content