It's been a bad day for Boris Johnson, but he could still ride out the Partygate scandal

British Prime Minister Boris Johnson has been fined for breaking strict lockdown rules to attend his own birthday party.

London (CNN)It's been said many times in the last three years, but this could be the worst day of Boris Johnson's political life.

It is now a statement of fact that the Prime Minister broke the law. He is thought to be the first British PM in history to be punished for doing so while in office and -- were he to follow protocol -- he would now resign from his post.
Downing Street has confirmed that Johnson has been fined by London's Metropolitan Police as part of their investigation into the so-called Partygate scandal. They said the fine was in relation to a gathering held on June 19, 2020, when Johnson's team held an impromptu gathering for his birthday at which he was presented with a cake.
    Under Covid restrictions in place at the time, indoor gatherings were not allowed, with people permitted only to meet outside in groups of up to six people.
      CNN affiliate ITV previously reported that two gatherings were held to celebrate Johnson's birthday on June 19: One -- attended by as many as 30 people -- held at the cabinet office in the afternoon, and another that evening hosted at Johnson's residence and attended by family friends.
      Downing Street said on Tuesday that on that date, Johnson had "participated in a gathering of two or more people indoors in the Cabinet Room at 10 Downing Street."
      Johnson has confirmed this did happen, but previously disputed that it was a gathering. In January, one of Johnson's key allies claimed that the Prime Minister had been "ambushed with a cake."
        It has been alleged that numerous other parties and gatherings were held in Downing Street and other government buildings at a time when the rest of the country was barred from meeting in groups due to Covid-19 rules set by Johnson's government. The Prime Minister has been accused of being aware of the gatherings and, in some cases, attending them.
        Johnson and his team have repeatedly brushed off all of the allegations leveled at the government. At one point, the Prime Minister's official spokesperson told journalists that "Covid rules have been followed at all times."
        Johnson apologized on Tuesday evening, saying that while he didn't think he'd broken any rules at the time, he respects and accepts the police's decision and has paid the fine. He said he would not resign, despite calls from all major opposition parties that he leave his job immediately.
        Speaking to Sky News Johnson insisted "it did not occur to me that this might have been a breach of the rules." He added that, having settled the fine, he would now "focus on the job in hand."

        Trivial or toxic?

        As trivial as a gathering with a birthday cake might sound, the scandal itself has been so toxic that Johnson being fined in relation to it is seriously damaging.
        It started on November 30 last year, when the Daily Mirror newspaper reported that social gatherings that could be described as parties were held in Downing Street during December 2020. Johnson denied that any rules were broken.
        Shortly after that, a video emerged of his former press secretary joking about a Christmas party in Downing Street. Johnson said he was "sickened myself and furious about that," but added "I have been repeatedly assured that the rules were not broken."
        Over the months that followed, more allegations emerged of wine parties in the Downing Street garden and Christmas quizzes, some of which Johnson was photographed attending. Downing Street claimed both events were suitably socially distanced.
        Arguably the most damaging allegation was that two parties took place in Downing Street the night before the Duke of Edinburgh's funeral. When news of the alleged parties broke, an image of Queen Elizabeth mourning her husband while sitting alone at the funeral, due to Covid restrictions, went viral.
        Queen Elizabeth II watches as pallbearers carry Prince Philip's coffin into St. George's Chapel on April 17, 2021.