I was speaking to someone who works in the Labour campaign for Rutherglen and Hamilton West the other day and we were discussing what it actually takes to build political momentum that’s irresistible. My take on it was you need three things: a bad guy, a buzz, and the facts. Two out of the three can get you quite far; you might even win in the end. But it’s only with all three that you get the great political shifts that happen in Britain every 20 or 30 years or so.

What seems to be happening to Labour in Rutherglen, in my view, is that they are some of the way there on the three factors but not all the way. They have the bad guys, in the Tories and the SNP (except lots of people still see the SNP as the good guys). They have some of the facts, which are talked about on the doorstep, hospital waiting lists being the biggie. And they have a bit of a buzz but not a big one: lots of people like Anas Sarwar and are kind of neutral on Keir Starmer. It’ll get a win in the end, so maybe that’s all that matters.

As it happens, whether or not Labour win Rutherglen (and I think they will) it’s quite a good time to apply a similar test to the Yes movement and work out where it is at the moment. As you may have noticed if you’ve been in Edinburgh, there was another independence rally at the weekend, organised this time by groups called Believe in Scotland and Yes for EU. As usual, there was doubt over how many people were there: the organisers said 25,000 (25,000!) but who knows how many it actually was and in some ways, it doesn’t matter: lots of people are passionate about independence and some of them were there.

However, the thing that strikes me about this rally is how different the landscape is compared to ten years ago. One of the other groups Hope Over Fear posted a video from 2014 of the songwriter Gerry Cinnamon singing his independence anthem in George Square. You may know the words: “Are you scared that the walls are too high to be breached by the bold? Will you stand and be counted or shut up and do what you’re told?” etc, etc. Gerry wore a saltire and the crowd loved it.

The reason Hope Over Fear was posting the video was to make an appeal to independence supporters to “recapture the spirit of 2014” and I kind of get what they mean. I’m not a supporter of independence (don’t drop your toast) but I distinctly remember the atmosphere in Glasgow nine years ago – the Yes badges, the saltires, the rallies – and I remember thinking: they’ve done it, they’ve won. You might even say there was a buzz.

The issue for the SNP though, and the Yes movement, was that the buzz in 2014 was big in Glasgow and Dundee and a few other places but wasn’t big enough right across the country. As I said, all the large political shifts – Thatcher in the 80s, Blair in the 90s – had a large national buzz around them, usually helped by a charismatic, convincing leader. Thatcher: yes. Blair: yes. Salmond: nearly. Sturgeon: nearly. Yousaf: no. In other words, 25,000 can gather in Edinburgh all they want, but if the buzz ain’t there, it ain’t there and that means it’s hard to see how they can “recapture the spirit of 2014” but more importantly build on it.

The second factor – the bad guys – is also now a problem for the Yes movement. Ten years ago, the SNP successfully painted both the Tories and Labour (or “red Tories”) as bad, and it worked partly because the leadership of Scottish Labour was ineffectual and uncharismatic. Ten years on however, that’s changed (a bit): Anas Sarwar appears to be going down quite well, he’s likeable, quite charismatic and doesn’t get rattled or ratty which is one of his great strengths. People got tired of Sturgeon’s snarling and Sarwar is a refreshing change; the hits that used to land on Labour also aren’t landing in the same way any more.

All of this means that, despite the saltires and shouting in Edinburgh at the weekend, the Yes campaign is currently failing on two of the factors a political movement needs to effect a big shift – buzz and bad guys – and on the third – the facts – it’s not much better. Thatcher won in ’79 because the economy was ruined and Blair won in ’97 because the Tory government was fagged out; people were worse off and wanted a change. These were the facts.

Three decades on, the problem is the facts are simply not on the side of the Yes movement in the same way they were for Thatcher and Blair. In his speech to the rally on Saturday, Humza Yousaf said Scotland wasn’t suffering from a cost of living crisis, it was suffering from a cost of the Union crisis, which is a neat enough line for his advisors to think of but it doesn’t accord with the facts as many people see them. People were struggling in the 80s and 90s and many saw Thatcher and Blair as the solution and people are struggling now and think independence could make it worse. They may also be on a waiting list, or their kid is struggling at school, or they’ve just seen their council tax bill, or they’ve seen the state of the streets in Glasgow, whatever it is, they’re starting to blame the SNP in a way they weren’t a few years ago.

That this is happening – the facts working against the SNP and the Yes movement – is backed up by the most recent polling and most worrying for the SNP, it seems to be happening most among the young and the middle classes. Polling by YouGov in May found that the SNP had the support of 52% of people aged 25-49 but that dropped to 38% in a poll carried out by the same company last month. As for the middle class, there’s been a similar drop in support of 11% among ABC1 voters and it’s serious stuff really. Support for independence may be relatively solid at 40something but if support for its main proponent, the SNP, is plummeting, what does it matter?

Do the people who attended the rally on Saturday realise this? Are they willing to accept it? Maybe not, but that doesn’t mean it isn’t happening. Mr Yousaf told the crowd “independence is the answer” – to high energy bills, cost-of-living, and everything else probably. But the real question, surely, is why the Yes movement isn’t making more progress. When he was talking about independence in his speech, the First Minister was heckled by someone in crowd who shouted “how do you we get there?” But perhaps a better question to have shouted would have been “why aren’t we doing better?”