Leading article: The test for Mr Cameron: will he take on his party?

It will come as no surprise that The Independent agrees with the majority of the recommendations in the Conservative Party's Quality of Life policy group report. We have been calling for such measures for several years now. Take aviation. The report demands the removal of effective tax breaks on flights and a moratorium on the expansion of UK airports. This is sensible. Aviation is the UK's fastest-growing source of carbon emissions. If we are to have any chance of slowing climate change, it is vital that the runaway growth of the aviation sector be curtailed. The argument that such measures would merely penalise the poor is weak. It is the middle classes, not the less well-off, who are responsible for the massive increases in the use of budget airlines in recent years.

The report also sensibly balances proposals for penalties on environmentally damaging behaviour with incentives for those who make more environmentally sensitive choices. For instance, it proposes that higher tax on fuel-inefficient cars be balanced by a substantially lower rate for smaller, cleaner cars. It calls for a reduction in council tax on energy-efficient homes and a lowering of business rates for greener offices. While air travel would become more expensive if the report were implemented, the travelling public would benefit from greater public investment in the train network. Despite the slurs of the vested interests in the transport industry, there is as much carrot as stick in this report as far as the general public is concerned. And the report's authors are careful to stress that there is no contradiction between economic prosperity and environmentally sound policies. Again, this is an approach The Independent has championed over the years.

David Cameron deserves credit for drawing attention to the plight of the environment since he became Conservative leader. Of course, he finds himself treading in the footsteps of the Liberal Democrats, the most consistently "green" of the major political parties. But most Liberal Democrat supporters have long been conscious of the need to protect the environment. By pushing environmental concerns so strongly over the past two years Mr Cameron has been going against the grain of his party. And this focus on the environment from the main opposition party has increased pressure on the Government to live up to its own rather modest promises in this area.

But despite the merits of these proposals, what matters now is that they are transformed into party policy. In recent weeks Mr Cameron has moved in a rather unsavoury direction, talking about "anarchy in the UK" and highlighting issues such as immigration and crime to appease his party critics. The question is whether this is merely a short-term stutter to shore up his position in the polls and fend off an early election, or whether Mr Cameron is retreating into the same reactionary comfort zone that doomed his predecessors.

If Mr Cameron wants to convince the electorate that he is fit to be prime minister and that his party has really changed, he must make a stand on green issues. He has to accept that the free market has failed to protect the environment and argue that a more interventionist approach is required if we are to confront climate change.

This will be anything but easy. Already there are complaints in his party over the implications of these recommendations. But to row back on his environmental pledges now would deliver a fatal blow to Mr Cameron's credibility. This policy group has furnished the Tory leader with the intellectual arguments for the adoption of a revolutionary environmental policy. He must now use them. The defining moment of Mr Cameron's leadership has arrived.