Everybody, supporters and opponents alike, used to agree on one point about HS2: it would be a colossal waste of money to build a fast railway that would run only between Birmingham and London. Even in the rose-tinted world of 2012, before the project’s projected costs exploded from £33bn, the government’s economic appraisal said the whole Y-shaped design, to Manchester in the west and to Leeds on the eastern leg, would be needed to make the cost-benefit ratios work. The logic was obvious: if the chief beneficiary is supposed to the north of England, you don’t build only the southern half. The critical review for government by Sir Douglas Oakervee in 2020 laboured the point. It was a make-your-mind-up moment for Boris Johnson’s administration because a notice to proceed (NtP) authorising HS2 to sign construction contracts for phase one alone either had to be signed or ripped up. “In essence, NtP is a go/no go for the entire HS2 project as the review has concluded that it only makes sense to do phase one if …