As change programmes go, HMRC’s was not just root and branch, it was trunk, leaves and the rest of the forest too, as the gargantuan task to modernise tax collection had changed little since the 1950s. With the £1 billion-plus failed white elephant that was digitising NHS records, still sending shudders through Whitehall, nothing could be left to chance and failure was not an option. What transpired was one of the biggest change programmes ever.