“I have three children,” Andrew Adonis told rail industry leaders in 2018. “A son, a daughter and HS2.” You’d be hard pressed to find a birth more traumatic than that of Lord Adonis’s third nipper. Currently £76 billion over its original budget according to leaks this week and 5 years behind schedule, the plan to create a new generation high speed rail network in Britain is shaping up to be a record-breaking white elephant. It is a bewildering mess.

How on earth did the costs get so out of control? Was it a case of overoptimistic costings at the start and bureaucratic bungling?