Politicians and leaders from around the world are among those to have sent congratulations to Boris Johnson and Carrie Symonds on the birth of their son.
Buckingham Palace said the Queen has sent a private message of good wishes to congratulate the couple.
And world leaders, including Australia’s prime minister Scott Morrison and Japanese premier Shinzo Abe, also sent their wishes.
Conservative former prime minister David Cameron – whose daughter Florence was born while he was in office in 2010 – sent his “heartfelt congratulations”, adding: “Sam and I are thrilled for you both.
“Sorry we didn’t leave the cot – but the climbing frame should still be in the garden.”
And Chancellor Rishi Sunak said it was “great to hear Downing Street is getting a new resident”.
Labour leader Sir Keir Starmer said it was “wonderful news”, while acting Liberal Democrat leader Sir Ed Davey sent his congratulations.
Scottish First Minister Nicola Sturgeon tweeted: “Some good news – sending congratulations to Carrie and the PM. And wishing health and happiness to the wee one.”
Arlene Foster, the First Minister of Northern Ireland, congratulated the couple, adding: “More sleepless nights ahead!”
Commons Speaker Sir Lindsay Hoyle congratulated Mr Johnson and Ms Symonds “on behalf of everyone in the House of Commons,” adding: “Such happy news amid so much uncertainty – 2020 is certainly a year they will never forget.”
The Archbishop of Canterbury, Justin Welby, tweeted his congratulations and prayers for the couple “as they welcome their son into the world”.
Commons Leader Jacob Rees-Mogg congratulated the prime minister for joining “an exclusive club” of MPs who are “fathers of six” after the birth of his latest child, saying it was a “great club to belong to”.
Mr Rees-Mogg told MPs: “As a father-of-six I know that there is no greater joy than a new life suddenly appearing in the room.
“It is a huge joy for the whole country.”
But ex-director of communications to Tony Blair, Alastair Campbell, told the that BBC while he congratulates the prime minister on the birth, there has been “too much of a focus on this almost like a personal soap opera, rather than one of the biggest national catastrophes that we’ve seen in our lifetime”.
Mr Campbell said he was worried the media coverage – mostly amongst the print media – will be “disproportionate” and that it was possible to wish the PM well, but “they’re not the royal family”.
He said he was not “mean-spirited” but that that it was important to “keep our perspective on the scale of the challenge”, citing the latest coronavirus death figures in care homes and job losses at British Airways.