It's a boy, no a girl - for Heather and Paul McCartney. Don't believe everything you read in the newspapers, especially Britain's Daily Mirror.

It got it spectacularly wrong when it announced the birth of a new baby for 61-year-old superstar Sir Paul McCartney's and his wife Heather Mills. Proudly revealing its world scoop, the front page banner headline screamed: "It's a boy! Exclusive - Macca baby a month early!" Except they got it wrong in one important little detail - the child was in fact a girl!

But the declaration by the Press Association a few hours later that the couple had become parents of a baby girl named Beatrice was all a bit late for the Mirror. It was also too late for the many other news media which ran with the Mirror's story. They included the BBC, Evening Standard, the distinguished Reuters and Associated Press.

The Mirror even speculated about the name the happy couple were going to give to their new "boy", quoting a family source suggesting it may be called Joseph after Sir Paul's uncle. Mirror Editor Piers Morgan's first reaction to the suggestion his paper had got it wrong was to go into denial: "We have an excellent scoop and we are sticking by our story. It's all very well for McCartney to say he has had a girl, but we need photographic evidence."

His infamous "It's a boy" splash headline will probably go down as one of the most prominent and embarrassing factual errors in the history of newspapers. Morgan revealed that the story originally came through the Mirror's sister paper the Scottish Daily Record. He said the blunder was a "tiny blip on a great scoop." An investigation had been launched into how the Daily Record and Mirror could have gotten it so wrong. "I suspect our tipster may have got an above-waist glimpse which may have caused confusion," said Morgan. He admitted that there was "a lot of egg on a lot of faces. The trouble with young babies is that they can all look very similar."

It's not the first time that a long-awaited and hotly discussed celebrity birth has been the subject of gender confusion. When former Spice Girl Victoria Beckham was pregnant with her second child, Britain was fully prepared to welcome a little girl, already known around the world as Paris, into the world. But the newspapers were forced to backtrack when Mrs. Beckham eventually gave birth to a boy named Romeo.