The vicious attacks on the Mr Johnson, who became a father again this morning, began when it emerged he would not be facing Keir Starmer at Prime Minister’s Questions. The hate-filled tweets even targeted Ms Symonds and the baby. Masses of tweets were deleted after it became clear the couple’s now boy was the reason for the Prime minister’s absence – but not before they had done their damage.

Labour MP Ruth Cadbury was among those accusing Mr Johnson of finding an excuse not to attend PMQs.

She quickly backtracked on her comments after discovering the couple had welcomed their first child.

A spokeswoman for the Prime Minister confirmed Ms Symonds, 32, gave birth to a baby boy at a London NHS hospital this morning.

Ms Cadbury, Labour MP for Brentford and Isleworth, wrote on Twitter: “It appears Boris Johnson has just found yet another excuse to miss #PMQs.”

Moments later the embarrassed Labour MP delete her tweet, and in another post said: “So Boris Johnson has a good excuse to miss #PMQs today – congratulations!”

But her initial remarks had already sparked a furious backlash from users on social media.

One disgusted user wrote: “Thank you for being a reminder why I will never vote for your shambolic party ever again.”

A second commented: “What an inhumane post.”

A third said: “You wonder why the electorate don’t want you in power, #Toxic.”

Several other anti-Tory users attacked Mr Johnson for choosing to spend the precious moment with his child rather than at the dispatch box.

One user said: “Breaking News. It’s official. Johnson fears Starmer and will not be appearing at #PMQ.

Another commented: “How many #PMQs has Boris Johnson missed since he became PM? It must be at least half. Anything to dodge scrutiny and responsibility I suppose.”

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The tone of the discussion on social media has been criticised be a number of users who insist the backlash is just a personal attack from left-wing anti-Boris activists.

But others leapt to his defence, one said: “Jesus! The PM goes into intensive care: The left on Twitter are vile. He comes out: The Left on twitter are vile. He becomes a father: The Left on Twitter are vile. These people really are very nasty. “

A second user commented: “Anyone thinking of having a pop at Johnson for missing PMQs should have a word with themselves.”

Foreign Secretary Dominic Raab stood in for Mr Johnson for the debate in the House of Commons.

The Prime Minister had just returned to frontline duties on Monday following his life-threatening battle with coronavirus.

It is understood Mr Johnson was present at the birth however details on the baby’s name, weight or where Ms Symonds gave birth are yet to be announced.

A spokeswoman for the Prime Minister said: “The Prime Minister and Ms Symonds are thrilled to announce the birth of a healthy baby boy at a London hospital earlier this morning. Both mother and baby are doing very well.

“The PM and Ms Symonds would like to thank the fantastic NHS maternity team.”