CTRL seems to have worked, so it's probably one of the few functional examples of a PPP that hasn't been a total disaster.

But I think you underestimate ideological hostility to trains in the UK. Rail has been the UK's biggest and most horrific soap opera in recent years. There is no evidence of strategic planning, and plenty of evidence that the Treasury has been trying to treat it was a way of clawing cash back.

As Afew said in a different diary, it's all about political calculation. Air is being developed for political reasons - it's a sop to the peasants who can holiday somewhere sunny. Road is all about Personal Freedom^TM.

Rail has neither of those advantages, and is seen as a huge cash sink - which of course of is, but mostly because of privatised inefficiencies and marketista nonsense.

While it's true the UK has practical problems with new lines that don't apply on the mainland, that didn't stop CTRL being a big success. So if the traffic is there - and it would be for a North/South route, and probably for a London/Cardiff route too - the right strategy can still make financial sense.

The point of all this being that actually getting people from A to B matters much less than the financial and political calculation that surround policy. And in the UK, policy is clearly hostile to rail, even if no one has come out and said as much in public.