It may just be the biggest Christmas gift Brits receive this year.

According to a close friend and former school pal, the former Kate Middleton – now the Duchess of Cambridge – is pregnant for the very first time.

Jessica Hay reveals Princess Kate and her husband Prince William will officially announce the baby news on December 12.

Hay told Life and Style Magazine that she has the news on the highest authority and it is not to be taken lightly.

“It’s going to be wonderful, happy news when it’s announced,” she said.

Hay and Kate were students at the exclusive Marlborough School, and she was a guest at the Royal Wedding reception on April 29, 2011.