The Commons Leader argued with opposition MPs on Thursday morning after insisting mask wearing was a personal choice, the day after it became mandatory to wear face coverings in shops and on public transport in England.
Speaking in the chamber, SNP Commons leader Pete Wishart urged Mr Rees-Mogg to “convince those menaces on the libertarian wing” of the Conservative Party to follow his lead and wear a mask in the Commons.
He said: “He and I were at the same meeting and we were told by Public Health England that if everybody on this estate wore a face mask, infections would be cut by 12 per cent
“So, no more excuses, masks on mushes.”
Mr Rees-Mogg replied: “I’m delighted [Mr Wishart] is so easily pleased.
“Had I realised that he would become sweetness and light merely by my momentarily wearing a mask, I may have been tempted to do it before the Christmas season or the season advent was upon us.”
Mr Rees-Mogg had previously declined to wear a mask in the chamber, but decided to do so amid concerns over the new Omicron variant of coronavirus.
He was confronted over the change of heart by the shadow Commons leader Thangam Debbonaire.
She said: “May I first of all say how pleasing it was to see the Leader of the House in a splendid-looking mask at Prime Minister’s Questions.
“It is nice that he has responded to the urgings from this side.”
The senior Tory replied: “She seems to have missed the fact that the rules on masks changed, which is why people are wearing them more and they are compulsory in public transport and in shops, but they are not compulsory in the chamber.
“It is a matter of judgement for people and people are entitled in this chamber not to wear them if that is the decision that they want to make.”
Ms Debonnaire also urged him to provide clarity on mask rules in schools.
Mr Rees-Mogg replied: “There is advice to schools that people may want to wear masks, older students and teachers, in communal areas, but people must make decisions for themselves.”
Mr Wishart had separately suggested Mr Rees-Mogg should “recuse” himself from discussions on standards reforms after it emerged the Commons Leader was subject to a probe.
Mr Rees-Mogg is one of nine MPs facing inquiries by Commons standards commissioner Kathryn Stone, along with Scottish Tories leader Douglas Ross and Lib Dem leader Sir Ed Davey.
Mr Wishart told the Commons: “Today it’s the Leader of the House who is all over the headlines as he emerges as the latest government minister to be investigated of his outside interests.
"Six million quid – I never knew he was so loaded.”
Mr Rees-Mogg said 16th-century legislation enabled him in his role as Lord President of the Council to sit in the House of Lords, adding: “It’s not a privilege I have ever taken up, I’m worried their lordships might be a bit surprised.”
The decision to investigate Mr Rees-Mogg came after Labour demanded an investigation into a £6 million loan that the party said he did not declare properly.