Nicola Sturgeon has no right to a second referendum on Scottish independence.  One took place only three years ago. The Scottish Government itself said that this represented a “once in a generation” vote.  The SNP didn’t win a majority in Scotland’s elections last year, and therefore has no mandate for a further referendum.  And polling suggests that most Scottish voters don’t want one anyway.

On paper, this case is persuasive.  In practice, it is less so.  It would be hard for Theresa May to refuse another referendum were Scotland’s Parliament to vote for one, which it will presumably do next week by passing a Section 30 motion, courtesy of the SNP plus the Greens.  The Prime Minister could perhaps argue that a referendum will not be granted unless the SNP wins a majority at the next round of Scottish elections in 2021, but it would be difficult to maintain that this condition is necessary if Scotland’s Parliament has already backed a poll.

May repeated her mantra yesterday of “politics is not a game” – and it follows that one should ask what she should do now to live up to her own slogan.  Half of the answer is to concede a second referendum.  The other half is to ensure that its timing makes sense.  Sturgeon’s proposed plan does not.  She wants a poll to be held between the autumn of 2018 and spring 2019.  This timetable may be in the interests of the SNP, but it would rob Scottish voters of an informed choice – for the simple reason that the terms of Brexit are unlikely to be clear by then, since the negotiations are likely to go down to the wire.

Sturgeon’s proposal would therefore see the people of Scotland decide without knowing what Britain’s post-Brexit future will look like.  They would be voting for a pig in a poke.  A sensible timetable would instead see a referendum held after Brexit, as Andrew Lilico said yesterday on this site, in either 2020 or perhaps 2021.  There is every sign that the Prime Minister gets the point, will take this view, and won’t repeat David Cameron’s mistake of allowing the SNP to dictate the timing of a referendum and the conditions under which it takes place.

It will be claimed that, by delaying any vote, May will stoke the nationalist vote.  Perhaps.  She would certainly do so were she to refuse a second referendum altogether.  But the key point is here is not to be lost in a forest of tactical calculations – all of which seek to manipulate a future which is by definition unknowable, and at a time when modern politics has seldom been so unpredictable – but to try to see the constitutional wood through the tactical trees.  If Scotland’s Parliament really wants a second referendum, it would be unwise to deny it one.  One then turns to the question of why Sturgeon is seeking one now, and what is likely to happen next.

The answer is that one cannot be sure.  It may be that she sees the next few years as her last likely opportunity to lead a referendum campaign – before Brexit takes place, the 2020 Scottish elections come, and the SNP perhaps loses its grip on office (and hence its chance to press for a poll).  Or it could be that she has been stampeded into calling for a poll by an older SNP activists in a hurry – we hope that Alex Salmond recognises himself – who see the next few years as a last chance to win their lifelong goal of an independent Scotland.

The single certainty is that the polls show no sustained majority for independence, and resistance by voters to a second referendum.  In these circumstances, it is impossible to know just who is bluffing whom.  Has Sturgeon got herself boxed in to seeking a second referendum by the declaration in her party’s 2016 manifesto that Scotland would be entitled to one in the event of Brexit?  Or is her nose more sensitive to the political wind than those of her opponents?  There is a faint but distinct sense that Sturgeon has built get-out clauses into her demand.  What will she do, for example, if May gains tariff-free access to the Single Market?

There is a case for saying that the SNP will lose any referendum, largely because the economics is so unfavourable to independence, and also one for saying that it will win, since there is more to politics than economics (as last June’s EU referendum confirmed) – and that the tide of Scottish opinion, which has been flowing towards independence for many years, will take the SNP over the winning line a second time round.  Again, one cannot know, and seeking to guess any outcome now is futile.

What is clear, however, is that while a Yes campaign is up and running – Sturgeon’s party is after all an institutional Yes campaign – the No campaign no longer exists.  It scattered to the four winds after the 2015 referendum.  This is ominous.  Furthermore, it surely cannot be reconstituted on the same terms as the last one.  Labour was then Scotland’s main opposition party.  This is no longer so, and it is far from clear whether it would be prepared to work with their replacement on the same terms as before.  This is, of course, Scotland’s Conservatives – and its brilliant, right-wing, left-field leader: our former columnist, Ruth Davidson.

Scotland’s Leader of the Opposition will recognise that to have her party in the front line of the campaign to keep the Union has its downsides as well as its upsides.  She will also know that a second No campaign cannot be all head and little heart, as the last one was.  As last June’s events proved, Project Fear campaigns don’t always work.  The Union needs to make an emotional connection with younger voters in Scotland in particular if it is to survive and flourish.

We will all have our own views on how this might be done.  Maybe Brexit provides an opportunity to offer a new version of Britain to Scotland – that of an outward-looking, globally engaged, free-trading country: Europe’s leading player in providing aid and peacekeeping, with its G7 membership and a seat on the UN Security Council.  But the truth is that only rigorous research can establish what pro-Union ideas and messages are most attractive to Scottish voters.  ConservativeHome’s sense is that the Government is now on the case, but it is very late in the day.  The heart-led case for the Union, as opposed to the head-led one, should have been started and sustained years ago.

Rigorous research needs rigorous reseachers – and campaigners.  The long and short of it is that the British team with the best recent record is the one that took on the might of David Cameron’s Government, with its track record of winning two previous referendums, and beat it.  Matthew Elliott led the research, with his Business for Britain project that morphed into Vote Leave.  And Dominic Cummings led the campaigning.  Neither are faces that should front the campaign for Union.  But were I Downing Street, I would be knocking on both their doors, and fast.