Dictated by profits

But her discretion holds no attraction for Business Secretary John Hutton, who believes that the answer to every question lies in whether private profits are at stake.

A third runway at Heathrow will be highly profitable for the construction and aviation lobbies, so to hell with the namby-pamby do-gooders who foresee problems with concreting over greater areas of the country and substantially increasing output of carbon emissions.

That is Mr Hutton's approach, which is at odds with the struggle to combat climate change and with his own government's insistence that it is intent on reducing greenhouse gas output.

Because his profits-at-all-costs creed is indefensible, he sets up a gallery of straw men in order to knock them down.

These include the supposed alternatives of no-one travelling at all or of only rich people doing so, even though such ideas would appeal, if they appeal at all, only to the most marginalised sectors of the environmentalist movement.

But, if such ideas are barmy, they are no barmier than Mr Hutton's belief that airports can continue to spread "to expand business from across the globe."

Faced with the reality that an aviation-centred economy will continue to have a deleterious effect on the environment, Mr Hutton pulls the rabbit of "greener flying" out of his top hat.

But he makes no attempt to explain this or to suggest how to make it happen, other than references to the usual "greater fuel efficiency" sales spiel from the plane makers.

Similarly unexplained is his dogmatic assertion that "we need a third runway at Heathrow. We are quite clear about that."

Mr Hutton's clarity apart, if the government was serious about its often repeated commitment to combating climate change, it would be doing everything possible to reduce unnecessary flights and to concentrate on more environmentally sound means of travel.

No fewer than 8 million flights took place from Heathrow last year to destinations that would have been easily reachable by train.

Had this switch taken place, it would have released 12 per cent of Heathrow's landing and take-off slots.

There are obviously problems with this proposal, especially over pricing, with many standard rail fares being more expensive than flying because of the government's cosseting of aviation, putting it in an advantageous position over taxation of fuel.

And the neglect of rail modernisation during the 1980s and 1990s, while much of Europe was investing heavily in new track and rolling stock, has left Britain with a lot of catching up to do.

However, previous failures to plan ahead should not be compounded by Mr Hutton's current obsession with short-termism.

If the government was to invest more heavily in rail, preferably under public ownership, improving and expanding the network, this would be a great contribution to a green future.

Ministers have to take a more long-term approach and to be more open-minded rather than being seduced by the siren voices of corporate profit.