As the designs for HS2 took shape, the new team behind it set out to prove its value to Ministers and MPs. But as Kate hears, long term flaws were being baked into the project, with an economic justification that centred on outdated assumptions. And, as the designers sought to make the justification, they adjusted the design - making it more expensive. The focus on speed was exciting - but it also distracted from the line’s real purpose. The initial vision was becoming more muddled by the minute.