Who would have thought that, in the difficult and divisive debate over the constitutional future of the United Kingdom, one of the issues that mattered was my car. My little blue Toyota Yaris. The 2008 automatic (one previous owner) that’s sitting outside my house. But it does matter. My car is an issue. I’ll explain why.

Specifically, what matters is my car’s licence plate. I hadn’t given the subject a second thought to be honest, but then Sir Tom Devine and the SNP’s Tommy Sheppard started getting upset, so I went outside and had a look and there it was. Down the left-hand side of the licence plate is a blue strip with the stars of the EU, the letters SCO, and a saltire. There I was, driving around all these years without noticing or caring, and it mattered. It really mattered.

The reason it matters, I’m told, is that the UK Government is poised to take away our Scottish licence plates. The Transport Secretary Grant Shapps said the other day that, because we’ve now left the EU, new registration plates will feature the British flag rather than the European one or the saltire. Mr Shapps said changing the design of the number plates was a historic moment for British motorists and a reassertion of our independence from the EU.

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Mr Shapps, of course, is talking out of his exhaust pipe – how can a change to licence plates be a historic moment? – but the reaction of the SNP was equally hysterical. Tommy Sheppard, who speaks for the party on the constitution, said it was absurd to put British flags on British cars and proved that Westminster was panicking over support for independence. “It highlights their desire to extinguish that by branding everything with a union jack,” he said. Mr Sheppard also said putting the union flag on cars owned by people who live in the union was flag-waving British nationalism.

The historian Sir Tom Devine was also unimpressed. Sir Tom said British flags on British cars would have been uncontroversial 50 years ago but many people in Scotland now preferred their own national symbols. He also predicted union flags on cars would undermine British unity rather than promote it. “According to recent polls on identity,” he said, “a significant majority of people in Scotland either feel totally Scottish and not British, or mainly Scottish and less British. This is further evidence that Downing Street is totally out of touch with feelings in the rest of the country.”

But here’s the thing: flags always have this kind of effect on otherwise sensible people. If you’re a flag-type person, if you care about that sort of thing, there are flags you like and flags you don’t like. In the eyes of Mr Sheppard, for example, using the union jack is flag-waving British nationalism, but what about using the saltire (as the SNP does on pretty much everything)? Is that flag-waving Scottish nationalism? Or is it entirely different? Why is one flag acceptable and the other isn’t if not for purely nationalistic reasons? Mr Sheppard can drop me a line with the answers.

Read more: SNP: The unholy alliance between nationalists and liberals

Sir Tom Devine’s position on the subject is also confusing. He’s obviously right that the views of some Scots have changed in the last 50 years, but I hope he won’t shout at me if I question the rest of his reasoning on public opinion. He says the polls show a significant majority of people in Scotland either feel totally Scottish and not British, or mainly Scottish and less British, but that’s only one way of looking at the figures. Turned the other way around, polls like the Savanta ComRes Tracker show the proportion who feel just Scottish and not British at all is only around 30%. Seventy per cent of Scots feel fairly, strongly or completely British.

This causes a problem for Sir Tom’s conclusion that putting the British flag on licence plates will undermine British unity or national feeling. Yes, some Scots, like Tommy Sheppard, will get worked up by the union jack on their cars, and we should probably just let them stamp their little feet about it. The rest of us – Scots who feel fairly, strongly or completely British – either won’t care, won’t notice, or will actually quite like the change. I suspect most won’t notice or care.

In underestimating British identity in Scotland (even the faint kind), Mr Sheppard and Sir Tom also fail to understand why the SNP lost the referendum in 2014 and have every chance of losing another one. Only the minority of Scots who reject British identity altogether voted decisively for independence, and the Yes campaign only won around half of those who say they are more Scottish than British. In other words, because you feel more Scottish than British doesn’t mean you’re going to vote Yes or give a fig about union jacks on your car. Indeed, Scottish voters’ attachment to Britain and British identity (even the faint kind) proved too strong for the independence campaign and will probably prove too strong for people to care very much about what kind of flag (if any) is on their licence plates.

What it also means is that Tom Devine is right about the union jack but for all the wrong reasons. We should – as Sir Tom says – avoid putting the British flag on licence plates, but not because it would undermine efforts to preserve the Union. We should avoid putting the British flag on licence plates for the same reason we should avoid putting Scottish flags on them. Flags create flag-wavers and flag-burners; they create lovers and haters; they create us and them.

In a country like Scotland – where our sense of national identity is “complicated” to put it mildly – nationalistic symbols of any kind are also best avoided. I am part of the majority of Scots who feel fairly, strongly or completely British, but I also don’t care about the little saltire on the licence plate of my 2008 Toyota Yaris. I also don’t much care if it’s replaced by a union jack. Much better, I think, to leave our cars alone. Much better to have no flags at all.

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