Have you seen the polls? Brilliant, aren’t they? YouGov has the Tories at 30 per cent, nine points ahead of Labour. If that’s not enough for you, Kantar (this one might be a bit dodge) has the Tories at 42 per cent, 14 ahead of Labour, and 17 up on where they were last time. Isn’t that brilliant? And if there are any elderly Germans reading, would you perhaps consider adopting me?

If replicated at a general election, the latter poll would potentially mean a Thatcher/Blair-size majority, which would enable Boris Johnson’s government to do pretty much whatever it wants. This is a bit of a worry because the things its senior members want include as hard a Brexit as possible, rethinking the NHS and bringing back hanging.

This morning we learned that another thing it wants – yes, this is me retreating to my comfort zone, and playing with trains, where it’s safe – might be to scrap High Speed Two (HS2). Transport Secretary Grant Shapps has launched a review of the new high speed rail link between London and the north, and has pointedly refused to rule out scrapping it.

At the time of writing, the British government has already spent an estimated £7bn on the thing, which, even in these days of parity with the euro, is rather a lot. But, says Shapps, who has clearly heard of the sunk cost fallacy: “Just because you’ve spent a lot of money on something does not mean you should plough more and more money into it.”

From a purely electoral standpoint, it must be very, very tempting to ditch HS2. It will cost a lot of money. It will involve digging up large chunks of rural England. And it’s widely hated by Tory activists.

The current government will get a lot of stick for it; whatever benefits it’s due to deliver will accrue to some other government, a decade or more away. And, let’s be honest, a lot of people can’t see the point of the exercise: why are we spending all this money just to shave half an hour off the travel time from London to Birmingham?

Well: we’re not. The real argument for High Speed Two has remarkably little to do with the “high speed” bit, and the fact the government has been failing to make the case for it doesn’t make that case wrong.

The real reason we need something a lot like HS2 can be summed up in one word: capacity. The existing rail network, especially the southern stretch of the West Coast Main Line into London Euston, is nearly full. To meet demand, and prevent ticket prices from becoming ever more exorbitant as train operating companies seek to manage that demand/exploit the people providing it, we need to be able to run more trains. A new north-south line, relatively speaking, is the easiest way of doing that.

There’s more. One of the problems with the rail network as currently constituted is that high-speed trains are often forced to use the same tracks as local ones, which places a hard cap on the frequency at which the latter can run if you don’t want trains to start banging into each other. This is one of the reasons so many cities have inadequate suburban rail networks compared to London. Divert the fast trains onto a new set of tracks, and you can run more local services, too. (There’s more on all this in Jon Stone’s excellent explanation of the scheme at the Independent, which you should read if you haven’t already.)

This doesn’t mean that HS2 is necessarily the right plan, of course. The high speed element has a downside – it means tracks have to be relatively straight, which means less flexibility over what you need to demolish. Major public works do tend to build up their own momentum, because those who’ve designed them have spent years working on their plans and so would be a bit miffed to learn it was for nothing. And it is very expensive.

So the idea of a serious review of the plan, to check it’s the right one and, hey, maybe even explain how its benefits aren’t simply “slightly faster trains to Birmingham” is not entirely crazy. The idea of scrapping it as if the whole thing has been a total waste of time, however, is idiotic. It will mean we’ve just pissed away £7bn in public money, it will make it harder to do a hundred other things necessary to keep Britain moving, and somewhere down the line another government will almost certainly be forced to do roughly the same thing anyway.

Short-termism is always a risk in British politics – but surely no government would be foolish enough to follow a policy that’ll do serious damage to the UK economy, just because the public don’t understand it, all in the hope of a fleeing political advantage...?

The previous paragraph is an example of the rhetorical technique known as “irony”. I mean, you’ve seen the polls, right? Bloody hell.