THE room where David Mundell and Ruth Davidson filled in the detail of Theresa May’s block on a second referendum has an unfortunate history for the Tories.

The panoramic top floor of the Point in Edinburgh was also where George Osborne delivered his infamous 'Sermon on the pound' before the last independence vote.

“Thou shalt not,” was the general thrust of his message then, just as it was yesterday.

Putting a question mark over Scotland’s currency undoubtedly helped the Unionist side win in 2014, but it also rallied and solidified support for the Independence cause.

Telling people they can’t have things is a risky strategy. It’s how backlashes happen.

As one expert put it: “I don’t believe that the UK government should go round threatening to block a second referendum. It would play directly into the Nationalists’ hands.”

That was Ms Davidson last September.

All such doubt has now been cast aside because of the crushing weight of Brexit.

The Prime Minister and her government are consumed by the most hellishly complex negotiations in modern peacetime, and the real spadework hasn’t even started yet.

The two years after the triggering of Article 50 will leave little room for other battles, and certainly not a campaign that could end in a Yes vote and a second constitutional crisis.

Imagine a vote for independence in late 2018 which forced the Prime Minister and possibly her government to resign a few months out from Brexit. It would be pandemonium.

So Mrs May has obvious reasons for wanting to avoid a war on two fronts.

With most polls showing a majority of Scots against a referendum before Brexit, she is trying to echo that back to voters: “Now is not the time”, rather than saying never.

However in politics reasonable messages invariably conceal shiftier manoeuvring.

It was also clear after Ms Davidson and Mr Mundell’s event that the Tories are not merely trying to park a second referendum until after Brexit, they want to dodge one altogether.

The plan appears to be to run down the clock until Ms Sturgeon's mandate to hold another referendum expires in May 2021, by setting a series of tests she cannot meet.

“At an absolute minimum, there should be agreement across political parties and from the public at large, that it is right and fair for such a referendum to proceed,” said Ms Davidson.

Given independence is as divisive an issue as you’ll find in Scotland, the prospect of “agreement across all parties” is remote to say the least.

It implies even the LibDem leader Willie Rennie could veto a referendum with a downward turn of his thumb.

Ms Davidson also said the SNP had to “earn the right to ask the question again”.

Asked to explain, her spokesman referred reporters to the 2011 election, when the SNP won a majority on a manifesto pledge to hold a referendum.

"Everyone could see they had a clear mandate to go ahead with it," he said.

If that’s the benchmark, it suggests the Tories won’t accept anything short of another SNP landslide.

The SNP leadership know what their opponents are up to of course.

The First Minister’s relaxed TV interviews afterwards Mrs May’s announcement suggested she wasn't taken by surprise, and had indeed factored this delay into her planning.

One senior SNP MSP said that if Mrs May’s hardline was not a starting position for talks, but her final word, then Ms Sturgeon might call her bluff and try for a snap Holyrood election.

With increasing dissatisfaction over health and education, the SNP know there may not be a pro-independence majority in the next parliament - hence Ms Sturgeon’s determination to have a referendum in this one.

But an election on the back of an anti-Tory backlash and resentment at Westminster lecturing Scotland on what it can’t have? Well, that could be much more interesting.