John Bercow taunts Boris Johnson and calls Brexit the biggest blunder since Second World War

Saga of leaving EU will - if it goes ahead - rage 'probably for the next 10 years and conceivably for the next 15 years', ex-Speaker warns

John Bercow has attacked Brexit as the country’s biggest blunder since the Second World War, warning it will take a decade to complete if it goes ahead.

The outspoken former Speaker said it would be “better to be part of the power bloc” – confirming Westminster’s worst-kept secret that he is a Remainer.

Speaking to foreign journalists, Mr Bercow – who quit last week – also attacked David Cameron and the “Conservative establishment” for undermining his pitch to win the Speaker’s chair.

He also turned his fire on Geoffrey Cox, the attorney general, after he branded the Commons a “zombie parliament” for challenging Brexit, saying: “Parliament is no disgrace at all and did its job well.”

And he taunted Boris Johnson over his humiliation when his attempt to shut down parliament for five weeks was ruled unlawful by the Supreme Court.

“What matters is the judgement of the Supreme Court. What matters is 11-0. You got it? 11-0. Maybe it’s not clear: eleven-nil,” Mr Bercow said.

The comments come after Mr Bercow stood down to be replaced by his deputy, Sir Lindsay Hoyle, after a tumultuous decade in the Speaker’s chair.

He championed the rights and power of backbenchers against the government - granting more emergency debates and urgent questions in the Commons.

But he enraged hard Brexit-supporting Tory MPs and ministers, who accused him of bias because he tore up precedent to rule against the government and allow the passing of laws to block a no-deal Brexit.

Several of the candidates to succeed him took aim at Mr Bercow, including Sir Lindsay, who said in his opening speech: “We've got to make sure that tarnish is polished away.

“That the respect and tolerance that we expect from everyone who works in here will be shown and we'll keep that in order.”

But Mr Bercow – who also revealed he will publish a book at the start of next year – strongly defended his record, saying: “No apology for championing the rights of Parliament.”

On leaving the EU, he said: “I don’t think it helps the UK. Brexit is the biggest mistake of this country after the war.”

And he added: “It’s better to be part of the [EU] power block than not. Crashing out would be extraordinarily undesirable.

The Brexit controversy will rage “for at least the next five years, very probably for the next 10 years, and conceivably for the next 15 years”, Mr Bercow warned.

And, on accusations of bias, he said: “Let me say for the umpteenth time, for the avoidance of doubt that I believe I was always fair in the chair.

“Fair to the Brexiteers, to whom I granted urgent questions and emergency debates before the word 'Brexiteer' had even been invented.”