An unqualified welcome is, I think, due to the stories in today’s press about Network Rail’s plans to assume industry leadership on the question of high speed rail developments.

It is increasingly clear that our existing network is becoming more and more congested as demand continues to grow. There are signs, too, of modal shift away from the private car and the aeroplane towards rail as fuel prices rise and people become more environmentally conscious.

Additionally, there is the fact that anybody who has used either the Eurostar or TGV realises just what a superb mode high speed rail is. St Pancras to Ashford in 20 minutes and to the tunnel in just under the half hour is pretty impressive by anybody’s standards – especially when you remember the old boat trains, which used to wander through the Kent countryside for what seemed like hours.

At its best, the UK’s InterCity network is very impressive, and improving steadily – the new high-frequency timetables planned for the West Coast and East Coast routes in 2009 and 2010 will no doubt represent another step change in service quality and capacity. The new InterCity Express rolling stock when it comes on stream in the next decade will mark another step forward, and the tectonic plates seem to be shifting once more in favour of main line electrification on the Great Western and Midland routes.

But where then?  That is the question which needs to be addressed.

Network Rail’s initiative, alongside the positive noises emanating from the Conservative Party, are both very welcome signs, and contrast sharply with the Department for Transport’s rather defensive approach, with Ministers twittering unhappily about the energy consumption of high speed rail and publishing misleading survey results about the public’s lack of desire to go faster.

So what are the arguments?  Well, the first thing to say is that going faster increases capacity, so providing room for more trains.

There is also the question of economic efficiency, productivity and market appeal: put simply, the less time people have to spend travelling, the more time they have to do other things – whether work things that improve national productivity or leisure things that enhance quality of life. And there is also the point that people who sit on trains can work, think and relax far more effectively than if they are driving cars or sitting around in airport terminals.

And lastly, there is the question of modal shift to more environmentally friendly and less polluting forms of transport.

TGV has virtually wiped out the domestic air market in France, and could no doubt do the same in the UK: already, Virgin has won huge numbers of passengers back to the train on the London-Manchester route – and significantly, 2006 was the first year for decades not to see growth in the volume of scheduled domestic air travel.  Just think of all that airspace and all those slots at airports, available to accommodate the growth in international travel without having to build a new runway at Heathrow.

A similar argument applies to car travel, and not just for long distance journeys either. Switching long distance trains to new high speed lines would release the capacity to enable all rail services to be improved, so equipping our networks to make an even bigger contribution to reducing congestion. In urban areas, we can combine this with other technologies such as tram-train to improve efficiency, market appeal and accessibility.

We do have to recognise that there would be some impact from the construction of new railways, as we have seen in Kent over the last few years. Indeed, in the past, much has been made of the argument about “our crowded island” and not being able to fit things in – it’s all right in France, the argument goes, they have plenty of land.

Ironically, of course, the most difficult bit of a new north-south high speed line – the route through the south east – is already available, with the former Great Central alignment being virtually in tact through to Rugby. And meanwhile the government seems quite happy to contemplate the major impacts of constructing new airport runways or widening motorways.

All in all, then, further initiatives in this field must be welcome. There is no doubt that the planning process – from conception to actually getting the ink dry on construction contracts - will be a long drawn out business. So the sooner we get on with it, the better.