Andrew Lilico is Executive Director and Principal of Europe Economics.

So, Nicola Sturgeon has, as expected, announced she will ask the Scottish Parliament for a second referendum on Scottish independence. She says that “if Scotland is to have a real choice…then that choice should be offered between the autumn of next year, 2018, and the spring of 2019”.

No-one should take seriously any suggestion that Sturgeon is only agitating for independence because of the UK’s vote to leave the EU. The SNP exists to promote independence, and after the 2014 vote was widely perceived as reasonably close, there was always likely to be another referendum within a decade or so, especially given SNP dominance at Holyrood.

Scotland is, of course, a country within the Union and thus (unlike, say, Yorkshire) it up to the Scots whether they stay. But that doesn’t mean it is up to the SNP to disrupt the economy and political society whenever it finds it to advantage to do so. If the Scots want another referendum, they should have one. But there’s no way the UK government — whose job it is, ultimately, to decide when referendum are held — should agree to hold one in late 2018 or early 2019.

First, is there any legitimate pretext for holding a referendum at all?

In 2014 Scotland decided, by a comfortable albeit not overwhelming 11 per cent margin, that decisions such as whether Scotland was in the EU should be made at UK level, not by Scotland alone. And that was not an undiscussed or wildly hypothetical instance of that principle, either. David Cameron’s promise of a UK referendum on Brexit was made in 2013 — long before the Independence referendum.

So the fact that, after Scots decided that decisions like Brexit should be made at UK level, the decision over Brexit was in fact made at UK level, is simply a direct and predictable consequence of the 2014 referendum. Arguing that Brexit happening despite a majority of Scots voting against is a reason for a second independence referendum is straightforwardly a rejection of the legitimacy of the first independence referendum result.

It is no surprise that the SNP rejects a referendum result that went against them. But no-one else should think that rejecting the first referendum result is a legitimate reason for holding a second referendum.

No. The reason for holding a second referendum is the reason a second referendum would have been held even if the UK had voted to remain in the EU, namely that Scottish politics did not regard the first referendum as having really settled the matter. According to opinion polls, most Scots believe there should be a second referendum even though most of them still say they would vote remain part of the UK.

So there should probably be one. But when? Sturgeon is asking that the referendum be held at the most disruptive moment possible. A referendum in late 2018 would mean serious campaigning through from about March 2018, around a year from now. That would totally disrupt the UK’s Brexit negotiations, allowing any EU member state seeking anything from those negotiations to attempt to play off Scotland against the UK government. It would mean the Brexit deal that the UK including Scotland secured would probably be a worse deal. It would mean domestic policy energies, already stretched by the Brexit negotiations and attempts to secure new trade deals with non-EU countries, would be diverted and diluted. Policy errors might well creep through.

All of that is what Sturgeon hopes for. The cause of independence — which is really all she cares about — would be served by the UK securing a bad Brexit deal for Scotland, and for the UK government to make policy errors in the meantime that Scots resent. An independence referendum just before or just after Brexit would also be at the moment in time when even the most pro-Brexit economists expect that the transitional disruption of adjusting to the new situation would be at its maximum.

And don’t be fooled by any notion that a pre-Brexit referendum would be a good idea because if Scotland voted to leave the UK it could stay in the EU. Firstly, if Scotland voted to leave the UK there would obviously have to be a transitional and planning period. That was expected to be at least 18 months for the 2014 referendum. So a September 2018 voted to leave the UK would not seek Scotland out until 2020 — a year post-Brexit. Even if Scotland were to leave the day after the vote, it took Chief European Commission Spokesman Margaritis Schinas about ten minutes to confirm that if Scotland left the UK it would have to apply to become an EU member; it couldn’t “stay” one.

Furthermore, according to opinion polls a large majority of Scots do not want there to be a second referendum pre-Brexit. There has been referendum after referendum in recent years: 2011; 2014; 2016. The poor Scots need a break! We can’t have a referendum every five minutes. Some of the time the SNP has to focus on running the schools and hospitals and roads and being held accountable for how badly it has been doing that.

Theresa May is the Prime Minister of Scotland. She should act like it, and act on behalf of and for the interests of Scots. The Scottish people do not want a pre-Brexit referendum — polls show that clearly. Having a pre-Brexit referendum could result in Scotland getting a worse deal in the Brexit negotiations and would be held at a point where Scots would have the least certainty about what the near-term future held. Why should they be forced to make such a huge decision under such unfavourable circumstances.

Sturgeon knows all this. She does not expect to get a late 2018 or early 2019 referendum. What she expects is to be turned down so she can manufacture a grievance out of it. Scottish voters are not stupid. They will see through this transparent ploy. The UK government should not be cowed by the argument that anything the SNP asks for it must get, otherwise that will foster a sense of grievance. What Sturgeon is asking for is stupid and counterproductive. She should be told no.

There surely will be another independence referendum. Let’s hold it a couple of years after Brexit, once everything has settled down and we have some idea what the future holds. 2022 could be a good time for that. Late 2018 or early 2019 are not.