Cheryl Cole logged on and tweeted with barely-concealed joy 'I'm sooooooo excited that we're having a royal baby!!!! Congratulations to Kate and Wills !!!!!!' (er, 'we'?)
While a jovial Olly Murrs wrote 'Cool #royalbaby that's amazing news!! Dam it how comes they never mentioned it on the XTRA Factor last week haha.' (Let's hope he consults a dictionary if he decides to pen an actual letter to the royal couple).
Serial-tweeter Phillip Schofield meanwhile fired up his iPad to reveal that his co-host Holly Willoughby had actually guessed the Duchess was expecting 'weeks ago'.
'Well done @hollywills. She guessed a week ago! Congratulations!' the This Morning frontman joked.
Dad-to-be David Walliams might be a bit concerned the Royal Baby will scupper any front-page stories of his own imminent arrival, but offered up his good wishes anyway, tweeting 'Congratuwelldone William and Kate. Very happy for you both. Dx'.
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And the newly-pregnant Saturdays singer Rochelle Wiseman posted 'Ahhhh yayyy Kate Middleton is pregnant - congrats xx'.
David Cameron meanwhile said he was 'delighted' by the news and that Kate and Wills would make 'wonderful parents'.
No word as yet from Britain's other 'royalty' though, Victoria and David Beckham. Wonder if Kate and Wills' news will make them really think about the oft hinted at baby number five?