It hadn't really occurred to me until George Monbiot's quite good piece about high speed rail, but I realised that it's not going to happen. None of the 3 main parties really cares about it.
How do I know this? Because there's no targets within the life of this parliament. No-one is going to be badgering them within a year or two about progress because journalists have no experience of being project managers so they don't get this. They'll just see the target a decade or more away and by the time we get there, the government can just blame it on someone before or circumstances or whatever.
In the mean time, high speed rail buys some votes from naive greens. At no cost. Genius.