The punchy new Transport for London boss Andy Byford, who comes with the background of knocking political heads together in New York transit (a perpetual war zone, basically), says that failing to crack on with Crossrail would make London “a laughing stock”. That charge hit home. The Prime Minister, as a former mayor, knows exactly why. You can mess up a costly Garden Bridge project and have a couple of airport ideas that don’t fly. But London will fall out of the league of confident, self-renewing cities if it fails to deliver on a key generational transport policy — and one which Johnson as mayor vociferously supported