Former House of Commons Speaker John Bercow has defended the backbench Labour MP who was kicked out of the chamber for calling Boris Johnson a liar.

       Mr Bercow said Dawn Butler was entitled to claim the prime minister had lied – calling for “absurd” parliamentary rules to be changed so MPs can accuse one another of lying in the chamber.

       Ms Butler was told to leave the Commons for one day last week after she refused to withdrawn her claim that Mr Johnson had “lied to the House and the country over and over again”.

       In a joint piece with the Labour backbencher, Ms Butler and Mr Bercow wrote: “The glaring weakness of the system is that someone lying to tens of millions of citizens knows he or she is protected by an ancient rule.”

       They told The Times: “They face no sanction. By contrast, an MP with the guts to tell the truth is judged to be in disgrace. It is absurd.”

       Ms Butler was ordered to leave the House for the rest of the day after refusing twice to take back her remarks, since it breaks current parliamentary etiquette to call another member a liar.

       She highlighted disputed claims made by Mr Johnson – referring to his statements on economic growth, NHS spending and nurses’ bursaries, before adding: “It’s dangerous to lie in a pandemic.”

       As explained on the UK parliament website, such language “breaks the rules of politeness in the House of Commons Chamber” and can lead to a member being asked to withdraw what was said or leave.

       In a chamber where MPs must refer to each other as the “honourable member”, accusations of deliberate deceit and dishonesty are forbidden.

       Many left-wing commentators and Labour MPs, including the party’s deputy leader, threw their support behind Ms Butler after the incident.

       “Just to confirm, Boris Johnson is a liar regardless of who calls him a liar or where they call him a liar,” Angela Rayner said.