David Cameron is proving to be a charmingly evasive public figure. Every day of the week I read articles demanding that Ed Miliband define his political purpose, or colourful obituaries of Nick Clegg's wildly oscillating career.

Curiously there is less scrutiny of the Prime Minister. Instead there seems to be a broad, but vague, consensus that he is a one-nation centrist leader in the Harold Macmillan mould, while someone called "Clegg" has tripled the fees for students and a figure known as "Lansley" leads a reckless revolution in the NHS. Mr Cameron is the decent chap who pops up every now and again to say how much he wants the poor to go to universities and admires those who work for the NHS.

Yet a judgement on a leader, especially a Prime Minister, cannot be based on whether he is a decent chap. The policies he seeks to implement, and the values on which they are based, determine a leader's public voice and role.

In this respect Mr Cameron's plans to transform the NHS are an important guide. I stress they are Mr Cameron's plans as much as Andrew Lansley's. After all, he is Prime Minister. He has known about them for years. If he disapproved or was worried about their impact, he could have done something about them. Instead, at the end of last year, he sought to reassure by asking his close ministerial ally Oliver Letwin to keep an eye on the policy. This was the equivalent of ordering Engels to check up whether Marx's Communist Manifesto was a practical programme. Mr Letwin was advocating the NHS reforms before Mr Lansley.

Oliver Letwin is one of my favourite politicians – thoughtful, polite, willing to engage, and achieving more of his policy ambitions than politicians that seek the limelight but make no practical change whatsoever. But he is also committed to policies that complete Margaret Thatcher's more tentative reconfiguring of the state. The NHS changes are central to his vision.

Over the past few weeks it has become something of a cliché to describe the plansfor the NHS – either enthusiastically or dismissively – as a revolution. For once the cliché merits persistent repetition. Mr Cameron's crusade goes well beyond putting taxpayers' billions into the hands of GPs, some of whom have enough to worry about already. As Nigel Edwards, acting chief executive of the NHS Confederation, noted in yesterday's Financial Times: "By 2014, the NHS will no longer be a system which still contains many of the characteristics of an organisation ... Instead it will be a regulated industry ... The Secretary of State will no longer have the power to intervene in NHS organisations which will stand or fail on their own ... there will be no power for the secretary of state to prop them up, or intervene if something goes badly wrong ... And unless a service is designated as protected, it will also be possible for a hospital or other healthcare provider simply to stop providing a service or operating a site from which it can no longer make money". Approve or disapprove, the policy marks the end of the NHS.

Tonally, Mr Cameron advances his case in the most reasoned manner, the very opposite of Mrs Thatcher's provocatively harsh style. He joked endearingly when he felt that John Humphrys was interrupting him on yesterday's Today programme, and stressed how much he valued the NHS and those who worked in it – an observation he contradicted later in the interview when he said that he was not surprised that the reforms were opposed internally because the competition would force staff to raise their game.

In his speech delivered after the interview Mr Cameron was the model of tonal moderation once more, copying Tony Blair's third way by arguing that the left was too preoccupied by the state and the right by the markets. Mr Cameron cited Mr Blair several times, and there is no doubt that the former Labour prime minister opened the door that Mr Cameron rushes through at dizzying speed. That is not in itself an argument in favour of the revolution, but it helps to give the changes an aura of pragmatic centrism.

The aura is deceptive. A centrist would not be so disdainful of context or practical consequence. Mr Cameron did not put his proposals to the electorate last May. Instead he promised there would be no more big reorganisations of the NHS, insisting that there had been enough of those. He must have known he was planning the biggest reorganisation in the institution's history, so the lack of candour highlights the degree to which Mr Cameron is committed to his NHS crusade. He was willing to risk being exposed as duplicitous in order to win power and then press ahead.

A leader following Macmillan's expediency or indeed Mrs Thatcher's calculated caution would act with more humility. She only started to speed up after her 1983 landslide victory, and she had won a fairly big majority in 1979. Mr Cameron secured no overall majority for his view that markets and the "big society" could take over some of the state's responsibilities. His excuse for the gap between what he said before the election is breathtaking in its chutzpah. He told the Today programme that what he meant before the election was that he was opposed to any change that turned out not to be a change, such as re-naming primary care trusts. This is not what he said or implied at the time.

His argument on the substance is superficially compelling: the Government is letting go, but patients will be in charge. They will have the choice to go to the doctors they want and the surgeons they seek. Until there is a surplus of good hospitals and GPs, such choice is an illusion. There will never be a luxurious surplus.

Perhaps there will never be a market to replace the NHS in the way that Mr Cameron currently envisages. As long as taxpayers fund health provision, and services are provided free of charge, governments cannot and should not let go entirely. Ministers raise the taxes and are ultimately responsible for how the money is spent. They cannot afford to let hospitals and GP surgeries go bust, and will not do so. Still, the advocacy is defining. In terms of the reform of public services, Mr Cameron is rooted firmly on the right.

s.richards@independent.co.uk

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