In a separate statement, he said of Sir Bernard: “He has no choice but to explain his actions to his own committee for his colleagues to investigate and then to resign.”

The last-minute interventions will – for Mr Johnson’s supporters – cast further doubt on the committee’s work. The former prime minister urged Ms Harman to explain what she intended to do about the charge “as Sir Bernard can no longer be regarded as a valid judge or investigator in these proceedings”.

The Telegraph understands the report will reveal the number of days the committee would have recommended for Mr Johnson’s suspension from the House of Commons.

As Mr Johnson has resigned as an MP, the sentence cannot be applied, but it will show how serious the offense was deemed to be. A source close to the committee said many will be surprised by how high the figure is.

It is clear that the committee concluded that it was not essential to Mr Johnson’s work to attend farewell events for colleagues – a central part of his defence.

The report could include a temporary or permanent suspension of Mr Johnson’s parliamentary pass – something former MPs retain when they leave the House of Commons.

To deprive a former Prime Minister of his ability to come and go on the parliamentary stand would be unprecedented. A committee source declined to say whether the move was suggested in the final report.

The report – a draft of which was given to Mr Johnson ahead of his dramatic announcement last Friday that he would be stepping down as an MP – is expected to be highly critical.

It will investigate whether he lied to MPs when he denied breaking Covid rules in No 10. Ultimately, the Metropolitan Police issued 126 fines for at least eight events in government buildings in what was described as partygate.

The committee is also expected to point to denials from senior Downing Street figures that they told Mr Johnson that no rules had been broken at events No 10. It is expected to criticize Mr Johnson’s allies for attacking of the committee process.