Michael McCarthy: And now for David Cameron's next trick ...

It seems incredible the Tories could abandon their love affair with nuclear fission

Like a green oasis on a desert horizon, a mouth-wateringly tempting political prize has become visible for David Cameron's new-look, think-outside-the-box, let's-try-anything Conservative Party: the dumping of nuclear power.

At first thought, it seems scarcely credible that the Tories could ever abandon their long love affair with nuclear fission. Political parties have particular shibboleths, and for the blue party atomic energy has long been an enormously powerful one. For Margaret Thatcher and her followers, it became an absolute article of faith, for several reasons.

It was not only that left-wingers tended to be against it, so that was a good reason to be for it. Mrs Thatcher herself had been a white-coated scientist in the mid-1950s when Britain opened Calder Hall, the world's first civil nuclear power station, and she saw it as a symbol of the UK's technological excellence; she had an instinctive sympathy for the nuclear industry. But more than that, atomic power generation played the vital role in the key domestic conflict of her time in office: it defeated the miners' strike.

After that, it became seen by the Thatcherites as almost sacred in nature. Support for nuclear power in the Thatcher circle was enthusiastic and unquestioning, and several of her officials, most prominently Sir Bernard Ingham, her press secretary, went on to work for the nuclear industry in lobbying and other roles.

Older Tory MPs still have these attitudes, a good number of them. But crucially, David Cameron and his close circle do not: they have a nuclear agnosticism which allows them to take an unprejudiced look at nuclear's pros and cons.

During the summer, the Government will almost certainly commit the UK to at least one more generation of atomic power stations as a replacement for the dozen or so ageing nuclear plants that currently provide about a fifth of our electricity supply. The driving force behind the move to new nukes is Tony Blair himself. The Prime Minister, who despite his one-time membership of CND has never looked askance at civil nuclear power, has accepted two arguments in favour of its extension.

The first is that, as we increasingly come to rely on imported gas for electricity generation, it makes sense to maintain a nuclear sector for reasons of security of supply. The other, whose chief proponent is the Government's chief scientific adviser, Sir David King, is that another series of atomic plants is essential in the fight against global warming, as they do not produce the large volumes of climate-changing carbon dioxide given off by conventional power stations burning the fossil fuels oil, gas and coal.

Environmentalists roundly reject these arguments, and consider that if the Government goes ahead with new nukes it will have blighted its green credentials irredeemably. They will fight a new nuclear programme tooth and nail; that will be one of the less appealing legacies Mr Blair leaves to Gordon Brown. In the past, Labour might at least have taken the consolation that it would have cross-party support for a new nuclear programme. But the signs are that Mr Cameron and his close supporters are increasingly impressed by the undeniably powerful arguments environmentalists make against atomic power.

Its economics are highly uncertain. Storing nuclear waste presents enormous, unsolved problems. The production of fissile nuclear material is a growing risk in a world where terrorism is increasing remorselessly. And mass investment for nuclear power may mean cutting investment for renewable energy sources such as wind and wave power.

Powerful though these arguments are, it would still be a huge step for the Tories to abandon the nuclear option: it would be almost like Labour abandoning Clause 4 on nationalisation (although that in itself may be an argument for doing it, to show how the party has really changed.)

However, there is one more argument that may well be the clincher. Imagine the moment, later this summer: just as the Blair Government announces its programme for new nukes, and excites the wrath of every environmentalist in the land, the Tories reject the nuclear option out of hand. No matter that they have solidly supported it for the past half-century. No matter that many Conservatives still passionately support it. The party leadership changes course, and politics is turned upside down.

Here's Labour suddenly painted into a corner as the pro-nuke party! Here's the Tories displaying dazzling environmental virtue on the issue that gets green-minded voters more worked up than any other!

Imagine the sensation! You can bet David Cameron can.