“Having decided to build it, we should get on and build it.”

National Infrastructure Commission chairman Sir John Armitt is talking about the HS2 railway. A natural diplomat, the angst the government has got itself into over the project is testing even his patience.

“The cheapest way is to build it as quickly as possible,” he adds. He thinks the suggestion that the first phase could be delivered over a longer period of time is folly. It will just cost more. “The more you spin it out, the more you’ve got future inflation. It creates more uncertainty.”