Britain is building one of the world’s most expensive railways

Most of the money isn't being spent on building a railway, it's being spent on not building it, such as by redesigning Euston station to be smaller and more expensive, repeatedly, and making sure to spend a large amount of money demolishing buildings and digging a big hole in the ground before cancelling it.

Make no mistake, this was deliberate Conservative policy. They knew (as everyone else did) that they were going to lose the last election, years before the fact, and chose to set money on fire and sabotage the country's infrastructure in order to make life harder for the Labour government that was coming and ensure they couldn't get a win.

Sorry but for some ballance, the current prime minister stood in parliament and opposed the entire HS2 project "on cost and merit" and voted against the project in 2016. He said "the only sensible plan is to abandon the project altogether".

> They knew (as everyone else did) that they were going to lose the last election, years before the fact, and chose to set money on fire and sabotage the country's infrastructure in order to make life harder for the Labour government that was coming and ensure they couldn't get a win.

Actually HS2 was never popular in Conservative constituencies and if they had a manifesto pledge to scrap the project entirely, they might've stood a chance.

There's a UK politics tradition called "kicking it into the long grass"

You've got a group of stakeholders who passionately believe X should be done. They've got some strong arguments, and some political backing. You've got another group of stakeholders who strongly think X should not be done. They've got some good arguments, and some powerful supporters.

So how do you resolve the debate? Which of the two groups are you going to upset? It's simple! You just delay the decision. Order a study, set up a committee, change the requirements, whatever. Just hold up any major works for 5 years or so without cancelling the project, and you can leave office making it some other chump's problem.

Nuclear power plant we might need, but it's expensive and nuclear? Long grass. Extra runway at a busy airport, but locals don't like it? Long grass. Decarbonising transport, but it'll raise prices? Long grass. Nuclear weapons renewal? Long grass. Incredibly busy road through a world heritage site? Long grass.

> Sorry but for some ballance, the current prime minister stood in parliament and opposed the entire HS2 project "on cost and merit" and voted against the project in 2016. He said "the only sensible plan is to abandon the project altogether".

That 2016 vote was the decision. Yes and no were both valid answers at that point ("no" was a bad one, but a defensible one). The subsequent dicking about is a whole lot worse than either.