Today’s guest blogger is David Henderson, of the Association of European Airlines in Brussels.

In the UK, we’ve just had party conference time once again, which means that the air transport industry can expect a good kicking, as a favourite political football.  This time around it’s the Conservatives, who want to swap Heathrow’s third runway for a high-speed rail line to Birmingham, Manchester and Leeds.  The political reason for action, of course, is environmental.

But it’s the numbers which intrigue me. Apparently these new rail lines will reduce Heathrow flights by 66,430 a year. Now the first thing I notice about that number is that it’s exactly divisible by 365, so someone has gone and counted daily flights and magicked 182 of them away. But which 182? I have to assume that all the Manchester and Leeds flights have disappeared (Birmingham doesn’t have any).  But that only adds up to 38.  The rest, we are told, will come from cuts in flights to places like Paris and Brussels, because passengers will switch to train services. Well, these places already have fast trains – and 60 flights a day.  The numbers don’t add up and neither does the logic.

If there’s one thing I love more than numbers it’s maps, and there’s a map of the rail plan on the BBC.  And to my surprise it’s not direct lines to three widely-dispersed cities but a neatly-drawn half-circle between the three.  So these 180 mph trains from Leeds to London will thunder through the centres of the second and third largest conurbations in the country – or, more likely, will slow down and stop.

But here’s the bit that really has me puzzled. These are not upgrades, they are brand new lines, to be built alongside the existing ones. Now roughly speaking, a rail line is about as wide as a runway, but whereas Heathrow’s third runway would be 2.2km long, the proposed rail link will be 400km. It will need vast tracts of land, not all of which will be uninhabited. It will need bridges and tunnels, cuttings and embankments – think of all those diggers, dozers and dumpers and then tell me about environmental impact.

These cities already have 125mph rail service – in the case of Leeds the new line would save less than half an hour travel time, the reason why they also have air links is to do with choice and convenience.  Not everyone lives next door to a rail station, nor has business in an office next door to a rail station.  You can speed up the trains by all means, even if it involves spending £15 billion of public money, but you can’t coerce passengers into use them – not without abandoning Tory principles of individual liberty and the market economy.