As my flying time amounts to ten minutes in a glider, I've always considered it unwise to post my opinions on this forum but, as you've touched on a subject I am very interested in, this time I couldn't resist.
As I live in Liverpool and travel fairly regularly to Birmingham and London by train, I am very well aware of the deficiencies of the railway system. In fact our train service to London is now appreciably slower than it was in the late 1960's.
The West Coast Route Modernisation aims to introduce 125 mph tilting trains that will cut the journey time down to just over two hours but we still have some years to wait.
Even so, the train service that we have at present amounts to 16 trains a day with a capacity equivalent to some 30 Boeing 747s and takes people from the centre of Liverpool to the centre of London.
What about the air service? Thats easy - there isn't one. We used to have a well-patronised service to Heathrow that was removed because the slots were required for other services. For several years, operators have been trying to relaunch the air link to the capital with little success - mainly due to the non-availability of peak time slots or the use of remote airports such as Luton.
At the same time, thanks to St. Stelios, we now have 5 services a day to Amsterdam Schipol, 3 a day to Paris CDG, 7 a day to Belfast,1 a day to Madrid etc. etc.
So if I were to give the two rival services between Liverpool and London a score out of 10, it would be 5 for rail and 0 for air.
Generally, rail can compete effectively with air where the journey time city-centre to city-centre is less than 3 hours. It, therefore, makes sense to concentrate resources on rail services where thay can reasonably achieve these times. London to Marseilles probably isn't a goer, London to Paris definitely is, as is London to Birmingham, Liverpool, Leeds, Manchester, Sheffield, Newcastle etc.
Remember also, that, with the exception of the Channel Tunnel Rail Link, no new trunk railways have been built in Britain for almost a century. The West Coast Main Line, mentioned above, was built in the reign of King William IV. They are an accepted part of the environment.
I don't dispute BahrainLad's claim that the new Channel Tunnel Rail Link Tunnel Rail Link will take up almost as much space as Heathrow - I simply don't know. What I do know is that the CTRL follows existing lines of severance (motorways and other railways) and, in environmentally sensitive areas uses cuttings and tunnels.
By contrast, Heathrow is an environmental disaster which blights a vast area of South London and, if a third runway is approved, will cause dislocation and disturbance for thousands of people (although my back yard will be safe).
Correct me if I'm wrong but I wasn't under the impression that punctuality was a major feature of air travel. I've made about 30 flights in my lifetime of which at least 6 were seriously delayed - by which I mean by hours not minutes, including one delay of twelve hours! The greatest delay that I have ever experienced in thousands of train journeys is 3 hours - and that was 25 years ago!
Rail services in Britain have suffered from being a political football for decades. I'm hoping that Network Rail and more sensible franchise agreements will work to stabilise the situation and giving Britain the second to none railway system that it once had and should have. Modern railway systems, as proved by the TGV in France, the ICE in Germany, the Shinkansen in Japan and the AVE in Spain are more than equal to any airline competition.