'Despite the rhetoric, and I can understand that every political party wants to distance itself from the other one, I do see that a lot of what is happening is building on the reforms of the early 1990s,' says Professor Alain Enthoven.

'We couldn't have imagined primary care groups if we hadn't had total purchasing pilots, and we couldn't have imagined TPPs if we hadn't had fundholders. The whole primary care side builds on what went before.'

The views of academics on NHS reforms past and present may be as common and as varied as pebbles on a beach, but Professor Enthoven is better qualified than most to offer his.

With the Conservative government mired in a review of the NHS sprung at short notice by premier Margaret Thatcher after the 1987 election, his ideas for an internal market gave health secretary Kenneth Clarke a solution.

The theory was put forward in a 1985 Nuffield Trust booklet, Reflections on the Management of the NHS. And it was to form the basis of a revolution that he, and others, believe has still not ended.

Professor Enthoven, now reflecting once again on the NHS from his base as professor of public and private management at Stanford business school in California, admits to liking some of Labour's reforms.

At present, he is constructing a lecture and new booklet - both to be delivered in November - for the Nuffield Trust, which is funding his travels, and is running his thoughts past academics and other policy makers in small forums.

'I think the emphasis on quality and information is very constructive and very positive,' he says. 'Likewise, with PCGs I can see the benefits, but I think it will take a good deal of time, resources, goodwill and effort to get there.

'I think it would be reasonable to expect something like 10 years to get all this into place. Look, for example, at reference costs: they started in 1991 and are still not completed and available.'

Fifteen years on, Professor Enthoven is still an advocate of market solutions - and regrets that the internal market was not given more time and political space.

'I think there is agreement that the purchaser-provider split was a good idea. It is, after all, remaining. There is agreement that trusts were a good idea. So I am sorry that time and politics didn't permit it to play itself out,' he says.

But he admits that things did not work out entirely as planned. 'The political constraints were stronger and narrower than I had expected. I was much less aware then than I am now of those constraints.'

Different national cultures played a strong part in that, he says. 'In America we do have our political constraints and problems, but I think there is more scope for the market to work, in part because we are basically a private enterprise-oriented society,' he says.

'We just don't look to government as much as people do here.'