There is, no doubt, particular joy in the atmosphere over a polluter who repents. And, indeed, the Government's abrupt, if belated, conversion last week to slashing the amount of carbon dioxide that new coal-fired power stations pump into the sky does provide cause for celebration.
Ed Miliband's announcement on Thursday that, in future, such plants must be fitted with equipment to remove the gas, has laid down a whole avenue of milestones. It is the single most important green measure yet by this Government. It is the first time that a Secretary of State for Energy has overridden the irredeemably pro-pollution position of his department. And, by establishing what can, and cannot, be built, it marks the end of laissez-faire energy policy in Britain.
Not bad for one short lunchtime parliamentary statement. But there is more. The new measures are likely to trigger a rapid increase in the use of the technology – cumbersomely entitled "carbon capture and storage" (CCS) – in the United States and worldwide. They could give Britain a share of a lucrative market that it seemed determined to forfeit. And they make it much less likely that the energy company E.ON will build its controversial new power station at Kingsnorth in Kent.
They certainly represent a tyre-screeching U-turn worthy of a boy racer. Not long ago John Hutton, Mr Miliband's predecessor as energy secretary, came within days of giving Kingsnorth the go-ahead as the first of six coal-fired stations in Britain. There was no question of fitting the technology – leaked emails showed the then Department for Business, Enterprise and Regulatory Reform colluding with E.ON to exclude it – and the plant would have emitted three times as much CO2 a year as the whole of Rwanda.
Worse, Mr Hutton and his predecessor, Alistair Darling, killed off a bid by BP and Southern and Scottish Energy to build Britain's first CCS plant in Peterhead. The Government was only prepared to consult on whether new power stations should be required to be "CCS-ready", so that the technology could be bolted on later – effectively setting aside room for it in the car park. Environmentalists protested that Britain was setting an appalling example to countries such as China and India whose coal burning threatens to send global warming spiralling out of control.
This all began to change at the last Labour Party conference, when Mr Hutton made such a pro-coal speech that he antagonised the hitherto dithering Prime Minister. He was moved to the Department for Defence to make way for Mr Miliband who – even more importantly – was also given responsibility for combating climate change, ensuring that it could no longer be disregarded when drawing up energy policy.
Thursday's announcement means at first, while the technology is still being fully developed, all new coal-fired power stations will be required to remove carbon from about a quarter of their emissions. But once the Environment Agency decides CCS is proven, which ministers expect by 2020, they – and all future stations – will have to use it completely.
In practice, up to four plants are to be given the go-ahead to try out the technology. Those chosen are likely to be along the east coast, so that the extracted CO2 can be pumped out to be buried in disused oil wells under the North Sea. Kingsnorth, say top government sources, has been reduced from a near certainty to an outsider.
Formally, the new policy is to go out to consultation, but it is virtually certain to happen, because, extraordinarily, it has been almost universally welcomed, with Greenpeace vying with E.ON, the CBI with the TUC to embrace it. And Conservative and Liberal Democrat policies are still tougher.
Even the radical Campaign against Climate Change hailed it as "a big move in a green direction", although it wants all plants to be fully fitted with CCS from the start. But then electricity generators would not have built any on grounds of expense, and paradoxically, the world needs them.
This is because China and India are likely to burn their coal – as their cheapest, if dirtiest, source of energy – whatever happens. So CCS, which removes 90 per cent of the CO2 from the fuel, must be got going as soon as possible.
Britain's decision is also likely to have the unexpected side-effect of boosting the uptake of the technology in the United States. A Bill now working its way through Congress would require US power stations to be fitted with full CCS, once it was installed widely enough worldwide. And the four plants now to be built in Britain, together with others planned overseas, would take it over the threshold.
Mr Miliband could, and should, have gone further. The Government's official Climate Change Committee wants CSS to be retrofitted to all existing power stations as well, and Scottish Power wants to prove this can be done at its plant at Longannet on the Firth of Forth. Only then will Britain get emissions from coal – mined here since Roman times – under control. But there must be a limit to the repentence to be expected on a single occasion from so unapologetic a government as this one.