JOHN Major has warned Boris Johnson that he could be dragged through the courts if, as Prime Minister, he suspended the UK Parliament to bypass MPs and force through a no-deal Brexit.

The former PM said it would be "utterly and totally unacceptable" for any British premier to shut down Westminster and he would seek a judicial review if it happened.

The threat from Sir John came as ITV announced that the head-to-head clash between Mr Johnson and his rival Jeremy Hunt attracted an average of 4.3 million viewers for the hourlong programme “Britain’s Next Prime Minister”. The programme peaked at 4.7m viewers, the broadcaster added.

Mr Johnson, still the frontrunner in the contest, has refused to rule out proroguing Parliament to prevent MPs blocking a no-deal exit from the European Union on October 31.

Sir John told BBC Radio 4's Today: "You cannot and should not bypass Parliament in this fashion. I cannot imagine how anyone could conceivably think that is right."

In order to prorogue Parliament, shutting it down until the next state opening, a PM would have to ask the Queen to formally allow it.

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Although the sovereign’s decision could not be challenged, Sir John said the PM’s advice could be.

The monarch would be "in the midst of a constitutional controversy that no serious politician should put the Queen in the middle of", declared Sir John.

"I for one would be prepared to go and seek judicial review to prevent Parliament being bypassed," he stressed.

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The potential suspension of Parliament was one of the issues on which Mr Johnson and Mr Hunt clashed in a televised showdown on Tuesday night.

The Foreign Secretary issued a stark warning about the prospect of suspending Parliament.

"When that has happened in the past, when Parliament has been shut down against its will, we actually had a civil war," noted Mr Hunt.

But Mr Johnson said: "I'm not going to take anything off the table, any more than I'm going to take no-deal off the table.

“It's absolutely bizarre at this stage in the negotiations for the UK - yet again - to be weakening its own position."

Sir John, who is backing Mr Hunt for the leadership, said: "There is no conceivable justification, wherever we are, in closing down Parliament to bypass its sovereignty.

"I seem to recall that the Brexiteers, led by Mr Johnson, campaigned in the referendum for the sovereignty of Parliament...They can't be concerned for the sovereignty of Parliament except when it is inconvenient to Mr Johnson."

The former premier was challenged over the timing of his decision to close down Parliament ahead of the 1997 general election, which prevented a report on the cash for questions scandal being considered by MPs.

Sir John said: "We carried the election until almost the very last date" and it was an "absurd charge".

The former Conservative leader, who campaigned to remain in the EU, warned the incoming PM not to stick rigidly to the "artificial date" for Brexit of October 31.

He warned there could be a "great deal of chaos" if businesses were not ready for a Hallowe’en exit.

Mr Johnson has made a "do or die" commitment to that date, while Mr Hunt has also set it as his goal.

"This date of October 31 has a great deal more to do with the election for leader of the Conservative Party than it has with the interests of the country and that is the wrong way round," Sir John argued.

"National leaders look first at the interests of the country, not first at the interests of themselves and appealing to a particular part of a small electorate for a particular post, however important that post may be."

Matt Hancock, the UK Health Secretary, who supports Mr Johnson, said he did not believe Parliament would be suspended because the leadership frontrunner had the "force of personality" to bring people together and reach a deal.

The Cabinet minister, who opposed prorogation during his own leadership campaign, told Today: "I do not think that it's going to happen, I understand why Boris hasn't ruled it out.

"But, ultimately, when you have to choose between who is going to be the next prime minister, who you want to be the next prime minister, you have to take everything into account.

"I have chosen to back Boris because he is the best person to deliver Brexit with a deal," he added.