Reacting to those claims on Tuesday, Johnson insisted that he could not fathom that "we would have gone ahead with an event that people were saying was against the rules," adding that he did not see the invitation to the party sent by Reynolds.

"Nobody warned me that it was against the rules ...

because I would remember that," Johnson emphasized.

Johnson added that "if I had my time again, I would not have allowed things to develop in that way," saying he would have asked the group gathered outside on May 20 to come indoors or told them "this isn't the right way to do things."

The Prime Minister continued to place the focus on the investigation into the parties being carried out by senior civil servant Sue Gray, saying she "should be given the space to get on and conclude her inquiry" and urging everyone with memories of the events to speak to her.