To the extent that the SNP’s current electoral popularity is due to pro-SNP (rather than anti-Labour) effects, it must be remembered that there is much more than independence at play. Does an SNP success in an election mean that Scotland has suddenly converted to the cause of independence? Of course not.

Firstly, support for independence is pretty low at the moment. According to the 2007 Scottish Social Attitudes Survey (which I believe asks a question about independence every year), support for independence (PDF link) was lower than it had been since May 1997. Asked to choose between independence, devolution or getting rid of the Scottish Parliament altogether, just 23% plumped for independence.

The peak of support for independence was actually in September 1997 — ironically, also roughly when Labour were also at the height of their powers. Then, independence was favoured over devolution for, as far as I can tell, the only time in history. Over the preceding decade support for independence has flitted up and down but has been in a pronounced decline since 2005.

Another point to note is that this, the SNP’s most successful period ever, has come at a time when the SNP has played down its support for independence. Take the slogan it has used since last year’s election campaign. Instead of things like “Michty me, we’ll soon be free” and all that sort of thing, their slogan was: “It’s time.” Time for what? Time for bed? The SNP don’t say.

You have to admit, it is a fiendishly clever slogan. Classic dog whistle stuff. So SNP activists and hardened advocates for independence think it’s time for independence. Anti-Labour voters see it and think it’s time for a change, time to kick Labour out. In fact, it can mean whatever you want it to mean.

Crucially, the independence issue was not rammed down people’s throats by the SNP. Given the closeness of last year’s election, that could well have been what swung it for them.

You should also bear in mind that the SNP are very far away from being a single-issue party. A vote for the SNP is not necessarily a vote for independence, and often an SNP activist will be the first person to tell you this. For instance, Richard Leyton got this line from no less a person than Nicola Sturgeon.

Don’t want an independent Scotland? It doesn’t matter. The SNP have made it very clear that independence will only come after a referendum victory. In the meantime, there is a “national conversation” about independence where you can express your views if you so wish. In effect, the SNP have tried as hard as possible to divorce the independence issue from Scottish Parliament and Westminster elections. The debate over independence now runs separately.

So what explains the SNP’s success? It’s the policies stupid. It is conceivable that Fifers who voted for the SNP did so because they were enticed by their promise to abolish the bridge tolls. Students may have been attracted to their promise to “dump student debt”. And of course, the people who felt that there should be a change in government were always likely to vote SNP because they are the second largest party in Scotland, and the only party in a position to stand up to Labour.

It must also be said that Alex Salmond’s leadership has a lot to do with the SNP’s current success. Yes, he splits opinion. But like him or loathe him, you have to admit that he is a great politician. He is good orator and has the charisma and leadership qualities necessary. The only other Scottish leader that can compare to him in my book is Annabel Goldie, and even she is pretty colourless compared to Alex Salmond.

Particularly when you compare him to the likes of Nicol Stephen and Jack McConnell, who both look permanently nervous, Alex Salmond towers above everyone else in the Scottish Parliament. Wendy Alexander was no match for him either, particularly given the state of disarray Labour are in at the moment. With Alex Salmond at the helm, the SNP should expect an upswing in fortunes, especially since their leader at the 2003 Scottish Parliamentary election was the dull and ineffective John Swinney.

Back in Glasgow East, from what I gather, the issue of independence was not completely ignored, but it certainly did not form a major part of the campaign. Instead, it was presented as a contest where the electorate would pass judgement on the records of the Labour Government in Westminster and the SNP Government in Holyrood.

The SNP were also hugely advantaged by the fact that they were already in 2nd place in the constituency. If my theory about whichever party being in a position to beat Labour will win is correct, then it is no wonder the SNP did well while the Lib Dems tanked.

Most votes are wasted anyway, especially under the FPTP system. But a sure-fire way to waste your vote in Glasgow East was to vote for the Conservatives or the Lib Dems. Only hardened Tories and Lib Dems who despise Labour and the SNP equally will have voted for them (or, indeed, any of the other smaller parties).

In summary, I think that the SNP’s victory in Glasgow East means almost nothing for the union.

That is not to say that I think that the status quo will prevail. I think I am right when I say that all of the parties currently represented in the Scottish Parliament, and the largest parties that are not represented in the Scottish Parliament, all support some kind of increased devolution to varying degrees. That includes the Conservatives, who appear pretty open to the idea of the Scottish Parliament having some leverage over fiscal policy.

Even Labour, painted into a unionist corner by their opposition to the SNP, have toyed with the idea of fiscal autonomy. Mind you, that was under the leadership of Wendy Alexander, who seemed to be a bit of a loose cannon when it came to trying to tackle the issue of the constitution. Who knows what direction Labour will take under their new leader, but I suspect that they will find it difficult to maintain support unless the take the majority view that the Scottish Parliament should have a greater degree of fiscal autonomy.

All of this, though, is almost incidental to the success or otherwise of the SNP. Increased powers for the Scottish Parliament will not come about as a result of SNP success. It can come about as a result of the success of any party.