SNP Westminster leader Ian Blackford is standing up for Scotland in no uncertain terms this week with his demand we should have the power to hold a second referendum on independence when the UK leaves the EU. In the last few days, The National has carried convincing columns on the same theme from pundits as diverse as the sound and subtle scholar Andrew Tickell to the former football firebrand Michael Stewart.

And they make a robust case. The Scottish Government acquiesced in the result of the first referendum on condition that underlying circumstances would not change. And Brexit, after we had been told a rejection of independence equated to staying in the EU, represents change fundamental enough to validate raising the issue once again. What’s more, the SNP’s manifesto in 2016 promised it would. By any standards, all this adds up to a mandate.

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Eager as I am to lend my own support, I still do not let my personal preference cloud the cold eye I try to keep on our politics. And the cold eye tells me that, given the present constellation of forces, there is no chance of an independence referendum this year or next year – in fact not before the term of the fifth Scottish Parliament runs out in 2021.

Principle is one thing, practice another. The maxim points to two reasons for expecting a later rather than earlier referendum. The first is that First Minister Nicola Sturgeon herself does not want an earlier one, at least not of the kind being called “wildcat”, in other words, do-it-ourselves without permission from Westminster, as proposed by deputy leader Keith Brown before his boss slapped him down. Nicola takes the contrary stance on cogent grounds. First, it is by no means certain that the Yes side would win a second referendum. Since the effort five years ago, with the result a 45-55% split, the polls show opinion among voters to be little changed.

Brexit could change it, and various asides from the First Minister show she hopes and expects Brexit to change it. But no such thing has happened yet. Till the actual outcome of Brexit becomes clearer, it is scarcely worth attempting a forecast. And we should recall that Nicola’s original target for a second referendum was a prospective Yes tally of 60%. Hungry militants may have forgotten that. I doubt she has.

Then, Nicola wants a second referendum to follow strictly the constitutional precedent set by the first referendum, in particular to gain prior consent from the UK Government under Section 30 of the Scotland Act 1998. It may not seem obvious why she has set this condition and that seems bound to make life harder for her or any future First Minister. But perhaps that’s the key to it. If we cannot win a second referendum, we may need a third.

Getting successive referendums will be easier if we are able to point to an established procedure for them, rather than having to make it all up from the beginning every time. I would myself be in favour of what the Swiss call “the initiative”, which means a referendum must be called if a certain proportion of the electorate sign a requisition for it – but that’s an argument for another day.

In any event, I think Nicola is right to maintain consistency on the matter of consent from Westminster. If we keep the whole business legal, there is no excuse for Unionists to sabotage it. They would have every pretext to boycott a wildcat referendum, leaving Scotland in the same deadlock as Catalonia. With a squeaky clean legal referendum, their jiggery-pokery would be foiled.

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Thus far, I have discussed the position of Nicola Sturgeon, but as things stand she is in reality not critical to the outcome. Under the doctrine of the absolute sovereignty of Parliament (a deplorable but effectual doctrine) it is UK Prime Minister Theresa May who has the final say.

“Now is not the time,” has been her line to date. In case anybody might think she had modified it, her Foreign Secretary, Jeremy Hunt, came to Glasgow last week to confirm that, if the Scottish Government asks for another referendum, the answer will “of course” be No.

I can read in the papers that May might not even last in office till my next column, so fraught for her will the events of today, tomorrow and the next day be. But even if she should fall, I would expect just as dusty an answer from those in the running to succeed her – certainly Hunt, and then Boris Johnson, Sajid Javid or Dominic Raab.

A different alternative is Jeremy Corbyn, if he comes to power literally because the Tory government has collapsed. But I don’t think that likely either, and he would in any case call a General Election at once, rendering all further extrapolation from the current state of affairs superfluous.

I’d stick my neck out and put my own money on May lasting her full term till 2022. And that’s the basic reason I think there will be no further progress towards a new Scottish referendum before then.

Logically, it cannot be otherwise, given the positions the two women at the head of our respective governments have staked out.

A further year or so would be taken up with passing the necessary legislation and running the campaigns. Then we are into 2023 or even 2024 for the earliest possible independence day.

Crestfallen Nats should reflect that this need not be time wasted. As I’ve written here before, I don’t think we are yet really prepared enough for another bite at the independence apple.

There have not been sufficient improvements on the failed formula of 2014 – there is no point in just shouting it louder to an electorate that has heard it all before.

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A thorough rethink is required on lines which, I fear, are little to the taste of the present generation in charge of the SNP. One would concern the narrowing of their vision since 2014 round the perceived interests and outlook of the west of Scotland, so that a region like the north-east seems simply to have been abandoned to its disaffection.

A second is the necessity of making independence as popular among women as among men. Male SNP voters outnumber females by two to one and to this end we have to concentrate on policies for home and family rather than on feminist grievance.

And finally we should forget about the pipe dream of equality in any economic, as opposed to a legal or political sense.

We enjoy full employment and our right priority lies in policies to improve productivity to get more out of our workforce for the labour they put in. This will at first generate inequalities, and rightly so, because it is how we can identify good practice, as opposed to bad practice, in our efforts to promote growth, which itself is the key to any subsequent redistribution.

At least there is time for the Scottish Government to grapple with the material realities of our situation rather than with feeble fantasies. Four or five years could do the trick. And then we might indeed hit 60% for Yes.