Ms Creasy tweeted on Tuesday evening: “Apparently Parliament has written a rule which means I can’t take my well behaved, three-month old, sleeping baby when I speak in chamber. (Still no rule on wearing masks btw).

“Mothers in the mother of all parliaments are not to be seen or heard it seems.”

Call for ‘further improvements’ to make Parliament family-friendly

Downing Street indicated Boris Johnson was in favour of the move to allow children in the Chamber, saying he supported a “modern, flexible” workplace that was “fit for the 21st century”.

Downing Stret said that he wants to see “further improvements” on making Parliament family-friendly, but stressed that ultimately it was a matter for the House.

Alex Davies-Jones, another Labour MP, said the warning left her and other mothers “hugely concerned”.

Ms Davies-Jones said the warning appeared to be a “contradiction” to Sir Lindsay’s assurance in January last year that he “wouldn’t be upset by” a mother deciding to breastfeed her baby in the chamber.

Caroline Lucas, the Green MP, said the rule is “absurd” and “absolutely needs to be challenged”, adding that babies are “far less disruptive than many braying backbenchers”.

Dominic Raab, the Deputy Prime Minister, said he had “a lot of sympathy” for Ms Creasy. He added that politicians need to make sure “our profession is brought into the modern world” so that “parents can juggle the jobs they do with the family time they need”.

‘Most workers can’t take their child into their workplace’ 

However, others questioned why they should do it in Parliament when it is not something that is allowed in other workplaces. 

Scott Benton, a Conservative MP, tweeted: “Parents who get paid a fraction of what you do pay for childcare and juggle responsibilities so they can go to work. What makes you so special?”.

Anna Soubry, the former Tory MP, wrote: “Most workers can’t take their child into their workplace – the office, building site, court room, hospital.”

She said that MPs were not employed in the same way as other workers, adding that “your cause may be right but the optics are poor”.

Jo Swinson, the former Liberal Democrat leader, is thought to have been the first MP to take her baby into the chamber during a debate, when she cradled her son on the Commons’ green benches in September 2018.