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Senior Tories seeking to block a no-deal Brexit are examining a radical plan involving the Queen, Newsnight has learned.

Highly placed figures in the rebel group are so concerned that the next prime minister could ignore the will of parliament that they have discussed a scheme to ask the Queen to intervene.

In a sign of the febrile atmosphere at Westminster, these Conservatives are thinking of holding a vote on a parliamentary device known as a humble address to the Queen.

If passed, the address would say that if the new prime minister ignored a vote rejecting no deal the Queen would be asked to exercise her right as head of state to travel to the next EU summit. Under their plan she would then request an extension to the Article 50 process.

Under EU rules, member states are usually represented at meetings of the European Council by a head of state or a head of government. The Queen is the UK's head of state, though it is understood that no European monarch has ever formally represented their country at an EU summit.

Buckingham Palace has declined to comment.

A request to the Queen to attend a European summit would be regarded as the most extraordinary political step in her 67-year reign.

It would probably be regarded as a breach of the unwritten rules surrounding Britain's constitutional monarchy, which say the Queen should be kept out of the political arena.

But the Tory rebels have discussed examining such a radical step because they have two fears about a Boris Johnson premiership:

He could press ahead with no deal by simply ignoring a vote in Parliament rejecting such a step. The rebels expect Commons speaker John Bercow will give them a chance in the autumn to change the law to ensure that Britain can only leave the EU with a deal

Boris Johnson could say he would abide by a parliamentary vote rejecting no deal. But the rebels fear he could then pick a fight with Emmanuel Macron to ensure the French president vetoes a UK request to extend Article 50

One Tory at the heart of planning to block no deal told Newsnight: "The problem is, what if Boris is so aggressive to the EU that Macron leads a charge to say just let the UK go? So even if Parliament votes to block no deal it could still happen.

"One option is a humble address to Her Majesty. You would ask humbly that Her Majesty requests an extension to Article 50. If that went through that would be seen as an instruction to her first minister. But what if the new prime minister refused to enact the humble address?

"Under EU law only two representatives of a member state can attend and negotiate on behalf of a member state at the European Council: head of government or head of state. So we could simply request that the Queen goes and submits the request for the extension."

The senior Tory told Newsnight that the idea of a humble address to the Queen is being examined seriously.

It is difficult to imagine the Queen intervening in politics so directly, even if the scheme was attempted.

So perhaps the eye-catching plan fits into the category of a device to put pressure on the next prime minister, rather than a mechanism to put the Queen on a Eurostar to Brussels.

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