Last summer, for the 60th anniversary of the NHS, the Nuffield Trust published a book in which key former secretaries of state for health gave their views as to whether the NHS should "rejuvenate or retire". There was considerable consensus on four particular points.

First, there was strong public support for the collective value underpinning the NHS - fairness. Second, that funding by taxation would remain for the vast majority of the population. Third, that the NHS was too big and too complex to be run by politicians. Fourth, that there should be a diversity of providers (not just those owned by the NHS) offering care to patients, and that some level of competition between them was healthy.

The recent advice to government by Mike Richards, recommending that individuals be allowed to pay privately for care not available on the NHS, without losing NHS entitlement, opens the door to allowing more people to supplement tax-funded care with privately-funded care. Former secretary of state Stephen Dorrell noted, "What has changed is the balance between the collective and the individual in society...and that is a challenge for the health service. To recognise that is not to walk away from its collective aspiration which...is overwhelmingly right."

The old battle lines, between those on the left, who believe in more funding, greater central or local democratic control to achieve improvements, and those on the right, who believe in privatisation and competition, are now very blurred. The debate is now essentially about two related things: power and levers.

First, what is the right blend of levers? In England, the political battle over the merits of allowing non-NHS hospitals and clinics to provide care to NHS-funded patients, and paying them according to the number of patients treated, has largely been won. This is still not the case in Scotland or Wales. Regarding direct financial incentives, central direction, regulation, local accountability, and encouraging stronger professionalism, research evidence is often not strong enough to give real-time answers as to where to go next. Instead we are left with experience (largely the domain of civil servants, managers and the few clinicians who engage in reform discussions) or instinct (largely the domain of politicians). While this can lead the NHS up some blind alleys, the long-term direction in England is surprisingly similar to that seen in other health systems across the OECD.

Second, to what extent should power be shifted from Whitehall and distributed locally to allow more innovation to flourish? Some argue that we need to break it up into manageable chunks; others argue that that will reduce fairness in access. So far the most meaningful step to allow local autonomy has been to liberalise hospitals - over half now are foundation trusts, where there is a legal lock to prevent Whitehall from interfering. The obvious future battle will be whether NHS commissioning should be similarly autonomous.

Jennifer Dixon is director of The Nuffield Trust