It could have been so very different. This general election campaign has so far been dominated by one woman. No, not Margaret Thatcher or her legacy, but another Iron Lady, the leader of the SNP, Nicola Sturgeon. No one could have predicted it, few can explain it, but let me have a go.

When Scotland voted ‘no’ by a larger margin than expected we all thought that was it. Alex Salmond had been firmly put back in his box and he had quit the stage. The SNP would shut up, and all would be well with the union. Not a bit of it. The Prime Minister’s vow, announced hurriedly in Downing Street at 7am with the ink on the ballot papers hardly dry, saw to that. Would he deliver or would he welch on it? Labour politicians piled in accusing him of making a promise he wouldn’t deliver on. He then compounded his error by going further and suggesting even more fiscal powers, including more powers to control income tax north of the border, giving Scotland effective fiscal autonomy. Labour went berserk and over the time votes Labour had lost to the ‘yes’ campaign became permanently lost to the SNP. Not only that but even Labour voters who voted ‘no’ began to look at the SNP in a different light and consider switching their allegiances. Opinion polls started to reflect this phenomenon and pundits started talking about the SNP gaining a dozen seats, then two dozen, then three dozen. One or two commentators even predict they will gain four dozen, meaning they will win every single seat in Scotland.

I admit it, I was slow to pick up on what was and is happening north of the border and anyone who spotted this trend on Matchbook.com could be in for a bumper payday. When I did my seat by seat predictions in January I predicted a total of 18 seats for the SNP. Looking at each seat individually (and I have done this for all 650, believe it or not, thereby proving my ultimate political geek credentials) I just couldn’t see how the SNP could overturn five figure Labour majorities. I can now. LibDem MP Jo Swinson, who has held the relatively marginal seat of East Dunbartonshire told me she has spent all her life fighting Labour, but they have now given up in her seat and she is now having to cope with fighting the SNP, who have recruited more than 1,000 new members there, many of them keen to take part in the campaign and defeat her. If she holds on it will be a miracle. My words, not hers. I don’t blame Matchbook.com or its customers for not running on a market on that constituency.

This is a phenomenon on Canadian proportions. For the younger among you that is a reference to the Canadian general election of 1993 when governing Conservative leader Kim Campbell became the least successful Canadian politician of all time by reducing the number of Conservative held seats from 156 to just two.

David Cameron has played into the SNP hands at every point of this campaign. His strategy (if you can call it that) towards the TV debates has given Nicola Sturgeon a profile she can only dreamed about beforehand. Had he taken part in three three way debates like last time, Sturgeon wouldn’t have been seen in a debate south of Hadrian’s Wall. Instead she is thought by most people to have ‘won’ both the national debates. People may not have agreed with all she said, but boy did she say it well.

The Tory campaign has developed into one in which they have nothing to say apart from to warn of the dangers of a Labour-SNP tie-up after the election. It’s a perfectly reasonable thing to do, but not to the exclusion of everything else.

So what’s going to happen? In my latest predictions I have the SNP on 41 seats, Labour on 11, LibDems on 4 and the Tories on 3. However, this weekend I will be revising that. I now think the LibDems face almost total wipeout and will retain only Orkney & Shetland and possibly one other. I’m reducing the Tory total also, and they may even face total wipeout. I also think that if things continue as they are over the next two weeks a few more Labour seats may fall to the SNP pushing their total to nearer 50. I think the betting line on Matchbook.com is about right at the moment: with over 50.5 rated at 2.35 (42.553%) and under 50.5 at 1.645 (60.784%). I see the overs shortening as events unfold in the next fortnight. I am told by Matchbook.com that currently 58% of the volume of bets has been placed on under 50.5 seats for SNP and that under 50.5 seats has gone from 2.0 to 1.64 (50% likelihood to 60%).

Make no mistake, one way or another Scotland is going to be the big story of election night, and it means it is impossible for Labour to form a majority government. The best Ed Miliband can hope for is to lead a minority administration, dependant on the SNP and LibDems for support in important votes. I believe that is the most likely outcome of this election and would reluctantly back the 2.63 (38.022%) priced for this on Matchbook.com. This heralds a whole new, and possibly very dark era in the governance of the nation. You have been warned.

This article first appeared on Matchbook.com