Former speaker of the House of Commons John Bercow has launched yet another scathing attack on Boris Johnson, saying he has "no redeeming virtues" and is "ritually dishonest".

He appeared on Sky News’ The Great Debate on Monday evening (February 14) and was responding to a question from host Trevor Phillips on if he would send the Prime Minister a love letter or a letter of dismissal.

Mr Bercow replied that he would send Mr Johnson a letter of dismissal "without hesitation".

He said: “Never has a prime minister wielded so much power, made so little effective use of it and been and been seen to be in quite such an indecent haste to blow his own trumpet.

“I’ve been aware of 12 prime ministers in my lifetime, by a country mile Boris Johnson is the worst.

“He is a narcissist, he doesn’t do the detail, he’s ritually dishonest – having a nodding acquaintance with the truth at best only in a leap year.

“He is responsible for a catalogue of failures, he is the most inarticulate public speaker and prime minister I have ever known, he has no redeeming virtues, he has stayed there far too long.

“It is time that he gave up office and beetled off into the distance, which would be an enormous relief – not just to this country and to the European continent, but to the world.”

Mr Bercow then joked: “And one of these days, Trevor, I’ll try to tell you what I really think.”

Mr Johnson has been the frequent target of Mr Bercow, who has repeatedly called him the worst Prime Minister he's seen.