THERESA May has appealed to Scots not to allow what she has called Nicola Sturgeon’s constitutional game-playing to “break the deep bonds” of the Union’s shared history and shared future.

But Angus Robertson, the Nationalist leader at Westminster, warned the Prime Minister not to break what he called her “promised agreement” with the Scottish Government – a term not recognised by Whitehall - before she triggers Article 50 to begin the Brexit process.

At a raucous Prime Minister’s Questions, Mr Robertson pressed Mrs May, saying: “Last July, she promised to secure a UK-wide approach - an agreement between the devolved administrations of Scotland, Wales and Northern Ireland and the UK Government - before triggering Article 50, so when will the Prime Minister announce the details of the agreement?”

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But Mrs May – just 48 hours after the First Minister seized the political initiative to announce she wanted a second independence referendum before Brexit happens in March 2019 – suggested Mr Robertson was comparing the EU, which had lasted 40 years, with the Union of Great Britain, which had lasted three centuries.

“We have been one country for over 300 years; we have fought together, we have worked together, we have achieved together, and constitutional game-playing must not be allowed to break the deep bonds of our shared history and our future together,” declared the PM to Tory cheers.

The SNP deputy leader hit back, saying Mrs May could “wag her finger as much as she likes,” but warned her: “If she does not secure an agreement before triggering Article 50, if she is not prepared to negotiate on behalf of the Scottish Government and secure membership of the single European market, people in Scotland will have a referendum and we will have our say.”

However, the PM urged Mr Robertson to “remember this: Scotland will be leaving the European Union either as a member of the United Kingdom or if it were independent as it is very clear from the Barroso document that it would not be a member of the European Union”.

Elsewhere, Downing Street described as “speculation” suggestions Mrs May is about to embark on a grand tour of the UK before she triggers Article 50 at the end of the month.

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It is thought that today the PM’s chiefs of staff Fiona Hill and Nick Timothy will be in Edinburgh to meet Ruth Davidson, the Scottish Conservative leader, and Conservative MSPs to talk about, among other things, the PM’s visit to Scotland and to guage the mood following Ms Sturgeon’s demand on Monday for a second independence referendum.

However, sources stressed that the visit by Ms Hill and Mr Timothy had been prearranged and was not directly connected with the FM’s announcement.

The language of Mrs May and her ministers is consistently pointing in the direction of the PM refusing to facilitate a second independence referendum this side of a Brexit deal because another divisive battle over the future of Scotland will greatly hamper the negotiations with Brussels and risk jeopardising the prospects of the UK Government securing a good deal for Britain.

Meantime, Jeremy Corbyn made clear that the PM should not seek to block a second independence referendum if Holyrood backed one.

A senior aide said: “It shouldn’t be blocked from Westminster; a decision to hold such a referendum is a matter for the Scottish people but we think and the Labour Party in Scotland is making the case that that referendum should not be held but, if it is held, we will be campaigning against independence on the grounds it would lead to turbo-charged austerity and there is no advantage to people breaking up the UK.”

Asked if the Labour leader still regarded himself as not being a Unionist, the aide replied: “The term Unionist has all sorts of baggage around it, which people are often keen to avoid in Scotland and elsewhere but the Labour Party under Jeremy Corbyn are in favour of maintaining the country together in the Union.”