John Bercow delivers the keynote speech at the 'Parliament and Brexit' conference in London on Tuesday (REUTERS/Henry Nicholls)

John Bercow has mocked Boris Johnson and his army of “eager beaver” Tory MPs, saying “they are wrong” if they think they will achieve a “strong Brexit”.

The former Commons speaker used a keynote speech in Westminster on Tuesday afternoon to attack the administrations of Johnson and Theresa May, while also defending Remainer MPs who challenged the fraught Brexit process in Parliament.

Bercow, who opened his slot at the Parliament and Brexit conference by parodying his own famous shout of “ordaaair”, was accused in his final years in the speaker’s chair of siding with Remainer MPs.

On Tuesday, he conceded the prospects of “parliamentary assertiveness” are now much less great because of Johnson’s majority won in December’s election.

In a parting shot, however, he said: “The Brexit negotiations, which I think are going to be fraught and difficult, are being led by the prime minister at the most proficuous time: early in the parliament when he has got the sun on his back and a very large number of new, aspiring, eager beaver Conservative MPs.

“They share his undiluted passion for what they consider a strong Brexit.

View photos Boris Johnson won a strong majority in December's election (AFP via Getty) More

“They are entitled to their views but in my personal opinion, they suffer a material disadvantage. They are wrong.”

After Britain left the EU on 31 January, the UK entered a transition period in which the government will negotiate its future relationship with the EU, including a vital trade deal.

View photos John Bercow speaks at the Parliament and Brexit conference (Reuters) More

Of the legacy of the 2017-2019 parliament, which inflicted numerous humiliating defeats on May and Johnson, Bercow said: “What I do not accept is the narrative that has come to be entrenched in large parts of the predominantly Brexit-supporting media that this paralysis [of the Brexit process] was the fault of those perfidious or treacherous MPs.

“The normal course of events is governmental initiation in parliament and control of the order paper. It was for the government to come and say what it wanted to do to implement its policy. And it didn’t. For two years after the referendum.

“That wasn’t parliament’s fault, of Conservative soft Brexiteers, of Remainer rebels, of the chair – that was the government which hadn’t made up its mind what it wanted by way of Brexit beyond the incessant articulation over a period of years of a slogan.”

Bercow, whose speech was punctuated with animated finger jabs for each key point he made, defended Remainer MPs who held back the government.

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“The only duty of an MP,” he said, “is to say or do what he or she thinks is right.

“I don’t accept the characterisation of the last parliament as rotten, useless. I think the last parliament was struggling to deal with the issue as best it could in the light of a referendum that told us nothing about what Brexit meant.

“I think my parliamentary colleagues were genuinely doing their best to try to get a better outcome.”