It's a boy! No, it's a girl! Newspapers get the baby blues

The editor of the Daily Mirror was adamant that all babies look the same from the waist up.

But Piers Morgan's powers of physiognomy did not prevent red faces all round yesterday when his newspaper welcomed the birth of Sir Paul and Heather Mills McCartney's girl with the front page headline: "It's a boy".

The BBC, London's Evening Standard and a string of international news agencies picked up on the story and launched serious discussions on the pros and cons of the name "Joseph", as reported in the Mirror.

The mystery surrounding the sex of the Beatrice Milly McCartney, born on Tuesday, was resolved only when the couple issued a formal statement at lunchtime yesterday. "She is a little beauty and we couldn't be prouder," they said.

"Our immediate family were told the news right away and are all as overjoyed as we are at the early arrival of our little bundle of joy."

As the couple settled down to enjoy the arrival of their daughter, questions were being asked and fingers pointed at media organisations in a somewhat redundant exercise of damage limitation.

Mr Morgan revealed that the Daily Mirror's story had been picked up from its sister paper in Scotland theDaily Record, and stated that an investigation had been launched.

"I suspect our tipster may gave got an above-waist glimpse, which may have caused confusion," he said. "There's a lot of eggs on a lot of faces. The trouble with young babies is that they can all look very similar. But it's a tiny blip on a great scoop."

The 7lb girl, who was named after her maternal grandmother and Sir Paul's aunt, was born three weeks early by Caesarean section at the Hospital of St John and St Elizabeth in St John's Wood - not far from the Abbey Road studios where the Beatles recorded many hits.

Beatrice is the first child for Lady McCartney, 35, but the fourth for the 61-year-old former Beatle, who had three children with his late wife, Linda. He also has an adopted step-daughter.

It is not the first time that a long-awaited and hotly discussed celebrity birth has been the subject of gender confusion.

When Victoria Beckham was pregnant with her second child, the nation had been primed by journalists to welcome a little girl, already known around the world as Paris, into the Beckham fold.

Newspapers were forced to backtrack when Mrs Beckham eventually gave birth to a 7lb 4oz boy, who the couple named Romeo.