Holyrood vote not in doubt - but what happens next?

Nicola Sturgeon and Theresa May Image copyright PA
Image caption Nicola Sturgeon said she was "frustrated" by her talks with Theresa May in Glasgow on Monday

This afternoon the Scottish Parliament will resume their debate on a Scottish independence referendum.

The debate was suspended and the vote delayed last Wednesday as news reached the chamber of the terror attack in Westminster. Today they will pick up where they left off.

The result of the vote this evening is not in any doubt. With the support of the Scottish Greens, the SNP will win the vote calling for a second referendum.

They will then claim that the prime minister must not stand in the way of the democratically expressed will of the Scottish Parliament.

But the other opposition parties - the Tories, Labour and Lib Dems - all believe that the will of the parliament does not match the will of the people.

Scottish voters don't want another referendum, they argue, and they are convinced public opinion is on their side.

It used to be received wisdom in Scottish politics that if Westminster tried to deny a Scottish referendum it could easily backfire and stir up support for independence.

Image copyright Getty Images
Image caption In general, independence supporters want another referendum while No voters do not

But the unionist parties are confident there is no great public demand for another vote - other than among people who are already committed nationalists.

Opinion polls suggest people are split fairly evenly, about 50/50, on whether they want another vote. And it tends to be Yes supporters who say yes to another referendum and No voters who say no, not now.

The great divide in Scottish politics over the question of independence may only be solidified by this current debate over whether to re-run the 2014 referendum.

Nicola Sturgeon will argue that this is now a great constitutional struggle in which the Scottish Parliament is battling with Westminster.

Tories say Ms Sturgeon is just playing a well rehearsed game, one in which she puts forward a proposal she knows will be rejected by Westminster and then responds with righteous indignation.

And we are about to see that happen once again. The first minster will soon send a letter to 10 Downing Street demanding another referendum.

No 10 will reply to say they are not prepared to talk about it at this time. The prime minister made that clear when she met Nicola Sturgeon in Glasgow yesterday, when she said it was more important to pull together and get the best Brexit deal for the whole of the UK.

The big question, the big calculation for both sides, is how many Scottish voters will then share the SNP's inevitable outrage about being denied another referendum.

Some will. Others will breathe a huge sigh of relief that they don't have to live through another campaign. At least not yet.