Geoffrey Lean: Brown talks the green talk... then gives us a new runway

You may be forgiven for missing it, but Gordon Brown had one bright spot in his worst ever week. At Monday lunchtime, before the data scandal, generals' attack, or the worsening of the Northern Rock fiasco, he made the most far-reaching green speech ever delivered by a British prime minister.

Long believed to be 'brown' by nature as well as name, he surprised his audience with both his rhetoric and his practical commitments. He announced a "world-changing mission" to tackle climate change, "the great project of this generation". He said that "the role of government from now on is transformed, changing its objectives from "economic growth and social cohesion" to "prosperity, fairness and environmental care".

He promised to build "a low- carbon economy", cleaning up transport, insulating one third of Britain's homes in "the biggest improvement in home energy efficiency in our history" and moving rapidly away from burning fossil fuels to "low carbon sources, primarily renewable ones".

Revolutionary stuff from any British premier, let alone this one, but it passed almost unnoticed. Abandoning their usual hype, his spin-doctors played it down. Why? Maybe it was just incompetence. But perhaps they thought he didn't mean it or that his measures would never be implemented.

True, the Prime Minister showed little sign of enthusiasm, dully reading his text. But far more damning was the way his ministers promptly behaved.

Take Ruth Kelly, the Secretary of State for Transport. No sooner had her boss promised that "every new policy will be examined for its impact on carbon emissions" than she proudly announced government plans for a third runway at Heathrow – which alone will be responsible for as much carbon emissions each year as the whole of Kenya.

Though Mr Brown had explained that greening the economy would provide "greater prosperity" she insisted that not building the runway would leave us "feeling purer but poorer". And she opined: "We shouldn't be in the business of telling people that one form of transport is bad and another good."

Similarly, Malcolm Wicks, the normally cocky Energy minister, was reduced to gibbering incoherence on Newsnight under questioning from Jeremy Paxman and the head of Greenpeace, John Sauven, on how the Prime Minister's words would be turned into deeds.

Mr Brown had, hours before, announced that the "technical transformation" of electrical generation away from fossil fuels must "start now". But Mr Wicks gave the firm impression that the Government would approve the building of the first coal-powered station in 20 years at Kingsnorth, Kent – even though it will annually emit three times as much carbon dioxide as the whole of Rwanda.

And that's not all. Mr Brown delighted his critics by saying he was "completely committed" to a tough European target of meeting 20 per cent of energy from renewables in just 12 years' time, despite a vigorous attempt by his Secretary of State for Business, John Hutton, to get him to sabotage it. But the Government won't outline how this is to be done for at least a year, by which time it will be even harder.

What is going on? Is the Government in disarray? Has the control-freak lost his grip? Or was it all just for show? None of the above, say Mr Brown's intimates. He has genuinely gone green, and radical policies are on the way. But the supertanker is only just beginning to turn. Let's hope so. The last thing the country – or the embattled Prime Minister – needs is a return to the false dawns, self-deception and dishonesty of the Blair era.