JOHN Major had vowed to go to court to stop Boris Johnson suspending parliament in order to pursue a no-deal Brexit.
The former prime minister said it would be "utterly and totally unacceptable" for parliament to be shut down, and that doing so would spark a constitutional crisis.
Boris Johnson is currently the favourite to win the Conservative Party leadership and succeed Theresa May as prime minister, but has refused to rule out proroguing parliament to ensure Britain leaves the European Union on October 31.
Major, an opponent of Brexit who has not shied away for criticising his party on the issue, told BBC Radio 4 that the move would require the Queen's blessing.
"In order to close down parliament, the prime minister would have to go to Her Majesty the Queen and ask for her permission to prorogue," he said.
"If her first minister asks for that permission, it is almost inconceivable that the queen will do anything other than grant it.
"She is then in the midst of a constitutional controversy that no serious politician should put the queen in the middle of. If that were to happen, there would be a queue of people who would seek judicial review.
"I for one would be prepared to go and seek judicial review."
Major accused Johnson of hypocrisy for backing Brexit to secure more power for Britain's parliament, only to propose to sideline lawmakers when it suited him.
He said parliament had not been suspended since King Charles I did so during the English Civil War. Charles was later executed in 1649.
"The idea of proroguing parliament is utterly and totally unacceptable from any British parliamentarian or democrat," said Major, who is backing Johnson's rival Jeremy Hunt for the leadership, though said he was speaking in a personal capacity.
Johnson responded by saying it would be "very odd" to give the judiciary a say over Brexit.
"I think everybody is fed up with delay and I think the idea of now consecrating this decision to the judiciary is really very, very odd indeed," he said.
'PARLIAMENT WON'T BE SIDELINED'
The question of suspending parliament was raised during a televised debate between Johnson and Hunt, the foreign minister, on Tuesday evening.
While Hunt categorically ruled it out, Johnson said he would "not take anything off the table".
Votes in parliament have indicated that a majority of lawmakers are against a no-deal Brexit because of concerns that it would cripple supply chains and damage trade.
The pound was trading near its lowest level for more than two years on Wednesday, as better-than-expected readings on the economy did little to dispel growing fears of a no-deal Brexit.
On Tuesday, lawmakers narrowly approved a measure that could make it harder for the next prime minister to suspend parliament.
House Speaker John Bercow has said it was "blindingly obvious" that the next prime minister would not be able to sideline parliament, adding: "Parliament will not be evacuated from the centre stage of the decision-making process on this important matter."
Major said there was a risk that Britain would not be ready to leave the EU in October, and that Johnson lacked leadership qualities.
He followed other party grandees in questioning whether the former London mayor was fit for the highest office.
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"National leaders look first at the interests of the country - not first at the interests of themselves," he said.
Majors own premiership, which last from 1990 until 1997, was itself plagued by Conservative disputes over Europe, and saw Britain ignominiously crash out of the European Exchange Rate Mechanism, the predecessor to the single currency, in 1992.
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