The pub garden smoking ban is a drag on our freedoms | David Mitchell

All the recent discussion of the pub garden smoking ban the government says it’s considering reminded me, I was surprised to discover, of Margaret Thatcher. A divisive figure, of course, but slagging her off feels a bit last-millennium. These days most people tend to take more of a “you’ve got to hand it to her” line. “I may not agree with what she did, but she obviously did agree with what she did and also actually did what she did, so fair play.” “She followed her beliefs, which is admirable” – although so did Hitler and, in his case, it is not admirable. It’s a flawed principle, then, the whole “fight for what you believe and that should be respected” approach. It’s only a rule of thumb – you still need to check your working.

Moving on from offensively putting Thatcher and Hitler in the same paragraph – and now the same sentence in a whole other paragraph – let me get back to explaining why the proposed pub garden smoking ban brought the Iron Lady to mind. It’s because I was reminded that, conviction politician though she undoubtedly was, she wasn’t above the occasional splat of political bullshit of the sort we tend to view as more of a 21st-century phenomenon. I’m thinking about the day she became prime minister when, outside 10 Downing Street, she quoted St Francis of Assisi. “Where there is discord, may we bring harmony,” she said.

It’s a nice phrase but it’s also pretty close to the diametric opposite of her approach. I think what she meant was: “Where there is discord, may my side of the discord prevail and my defeated enemies learn to live with it.” The whole Assisi vibe turned out to be astonishingly insincere. Similarly, this pub garden ban took me back to the current prime minister’s own words outside 10 Downing Street on his first day when he promised a government that would “tread more lightly on your lives”.

In Starmer’s vision, is a welfare state only affordable if the populace is compelled to be prudent?

I loved that. That was exactly what I wanted to hear and hadn’t been expecting to. Not only was it a deft dig at the noisy squalor of the Johnson-Truss-Sunak era, it also allayed the fears a lot of people have about left-leaning governments: that they’re bossy and they interfere. They think they know best and try to make you do what they want. The Tories relentlessly accuse Labour of secretly planning tax rises but I don’t think that’s what worries floating voters most. The Tories are obsessed with money and assume everyone else is – but some things are more important. In the days of the iron curtain, the countries of the west were demonstrably richer and more prosperous than those in the Soviet aegis, but that wasn’t the reason most of us feared communism. It was the eastern bloc’s lack of freedom, not money, that terrified westerners.

That’s why I thought it was an astute promise for Starmer to make, but if he goes ahead with a ban on smoking in pub gardens, it will be reduced to the level of Thatcher’s pledge of saintly harmony. For smokers and publicans, that will be a heavy tread – an unlooked-for stamp – of far greater significance than the likely capital gains tax hike that is going to send the Conservatives shrieking and clutching their pearls.

The indoor smoking ban was bad enough. I know it’s been successful at reducing smoking and, on balance, I wouldn’t go back on it now. Nevertheless it is my belief that that is not the sort of law governments should make. Smoking is a stupid thing to do but, in a free society, we should be allowed to do stupid things unless they impinge on the freedom of others. But the advocates of the ban tried to claim that it was not an assault on liberty, by citing the health impact of passive smoking.

Are they really going to make the same claim when it’s being done outdoors? That smoking in pub gardens significantly shortens the lives of significant numbers of non-smokers? More than driving non-electric vehicles or smelting steel or lighting bonfires on 5 November, activities the government is not proposing to ban?

Feeble though that argument would be, it is troubling to me that it is not how Keir Starmer proposes to justify the ban. His reasoning is more radical. He thinks it should happen in order “to reduce the burden on the NHS and reduce the burden on the taxpayer”. So he proposes to place legal restrictions on unhealthy behaviour in order to cut down what it costs the state to provide medical care. “That’s why I spoke before the election about moving to a preventative model when it comes to health,” he explained.

Related: I love the nanny state, but let’s leave outdoor smokers to puff away in peace | Martha Gill

This is chilling. I assumed the “preventative model” meant things like offering regular checkups, screening for cancers and encouraging healthy lifestyles, not placing legal barriers in the way of unhealthy ones. That sets quite the precedent: the state will stop you doing things that are bad for you in order to mitigate its hospital spending. With that principle established, what liberty might not be curtailed: fatty foods, contact sports, sexual promiscuity, motorbikes, stressful jobs? All this stuff could place a burden on the NHS and the taxpayer. In Starmer’s vision, is a welfare state only affordable if the populace is compelled to be prudent?

I don’t really believe he’s contemplating taking it that far. Smoking has been demonised to the extent that it’s no longer considered in the same category as other freedoms. Plus, Rishi Sunak’s proposal to ban the sale of tobacco to everyone born after 2008 – which was clearly the desperate attempt of a hapless mediocrity to regain control of the political agenda, but a policy now adopted by Labour – has effectively given the green light to more restrictions. It’s politically far safer for Starmer to curtail smokers’ rights in a way Stalin himself would never dare than it is for him to, for example, say what he really thinks about Brexit. I’m relieved the Tories lost the election but our political system remains ridiculous.

• David Mitchell’s new book, Unruly , is now out in paperback (Penguin, £10.99)