In an unprecedented move, UK Prime Minister Boris Johnson is to be investigated for potentially lying to MPs over parties said to have been held at Number 10 during Covid lockdowns.

       Mr Johnson had previously told MPs that the "rules were not broken" at Downing Street.

       However, he has since been fined by the Metropolitan Police for taking part in his own birthday party in June 2020, at which time UK government pandemic regulations banned indoor gatherings between more than two people.

       So what exactly will an inquiry into Mr Johnson’s behaviour entail? And what could happen to the prime minister if he is found to have lied to the Commons?

       Leader of the opposition Sir Keir Starmer said it has ‘never been more clear that Boris Johnson’s authority is shot and he is unable to lead.’

       (UK PARLIAMENT/AFP via Getty Imag)

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       What happens next?

       The passing of the motion means that MPs on the Privileges Committee will investigate whether Mr Johnson is in contempt of parliament for misleading the Commons with his repeated denials of lockdown-breaking parties.

       The probe won’t start until after Scotland Yard has completed its own inquiry into alleged Covid breaches at the heart of Government, after 5 May.

       Scotland Yard, whose investigation into lockdown-breaking gatherings is ongoing, said that the 5 May local elections meant that they would not make any further announcements about fixed-penalty notices until after polling day.

       However, Number 10 suggested that it would declare whether Mr Johnson or Cabinet Secretary Simon Case are issued with fines, in the run up to the local elections.

       The PM’s own MPs refused to defend him on Thursday in the Commons and it is thought that this may trigger the release of damning photos of his alleged illegal gatherings.

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       What could this mean for Boris Johnson?

       Number 10 conceded that as part of the inquiry, hundreds of potentially damning photos and documents may be released. Neither the Metropolitan Police nor the Sue Gray inquiry was expected to disclose them.

       Having taken evidence in private, the committee will be expected to make recommendations to the Commons.

       It may be recommended for the prime minister to be suspended, should it be found that he misled MPs intentionally.

       If it were to come to this, the pressure on Mr Johnson to quit would be intense.

       However, should the committee decide that any misleading was accidental, the whole thing could potentially blow over and Boris Johnson may remain as PM.