For much of the last 20 years, public health has faced a huge challenge of marginalisation. A state active model of health was always going to struggle under a government that denied the concept of society.

Then came a New Labour government focused initially on waiting lists and waiting times. By definition, they were more concerned with acute care activity than the core public health interests of improving health and avoiding illness. Now public health is facing a new challenge: that of being at the centre of health policy.

The world class commissioning competencies set out a number of areas where public health skills and knowledge have a crucial role, particularly needs assessment and knowledge management. Historically, a public health profession that chose to specialise in population impact and cost effectiveness rather than individual treatment has been an important source of expertise and advice for commissioners, notably in supporting prioritisation of investment.

However, a policy focus on the individual and the commitment to the notion of "rescue at any cost", as well as access targets, has continued to distort heath investment. Now joint strategic needs assessments and robust databases identifying health need, variability in access and outcomes will lay bare health inequalities. In this context, it will be increasingly difficult to claim an interest in health improvement while continuing to invest in traditional interventions at legacy proportions.

A key element of knowledge management is the understanding of local epidemiology and an intervention's health benefit and return on investment. In the context of a defined budget allocation and a challenge to improve health, it is no longer sufficient to argue that£25,000 per quality adjusted life year is a reasonable investment also considering the cheaper interventions for larger numbers. These will have to be rationed in order for a defined group with special and expensive needs to benefit. Successive commissioning reorganisation has the loss of significant public health expertise and capacity. Increasingly, the role has retreated into health promotion: the result of a natural desire to find a way of intervening locally.

A key proverb for public health is the story of the man who stops leaping into the river to drag drowning people out one by one and instead walks upstream to find out why they are falling in in the first place.

But the shift into small scale community interventions has limited evidence in relation to system change. In recent challenges to "spearhead" primary care trusts, the National Support Team for Tackling Inequalities has expected to see public health knowledge about targeted activity at a local level, coupled with management expertise in investment, programme management and delivery.

The risk here is that public health has too effectively embraced its marginal role, frequently challenging PCTs and their predecessors for failure to address health inequalities and poor investment, as though the public health department sits outside them. As we assess the real impact of PCTs on tackling health inequalities and health improvement, those teams who have stepped down into the mire of commissioning, finance and service improvement can feel proud of their achievements, while those on the high moral ground may feel a bit chilly.

This is a very exciting time for all of us as public health practitioners. Many of the national levers for health improvement are coming into place for the first time. These include:

  • Commitment to partnership in recognition that the determinants of health largely sit outside NHS control (with local area agreements challenging public targets for life expectancy, smoking cessation and teenage pregnancy).

  • Key competence in investment for commissioners.

  • Political leadership which prioritises not only health improvement and upstream investment but explicitly challenges us as a service to tackle long-standing health inequalities.

However, moving into the centre of policy activity also requires us to take up our full corporate responsibilities for leading change into some uncomfortable territory.

We shall have to collaborate to deliver the necessary levels of analysis and knowledge management.

We have some good infrastructure in the public health observatories and regional health protection agencies but need to actively commission these to deliver for the local PCT, as well as that which is intellectually interesting for the specialist professional.

The new Public Health Network has a key role to play. A steering group of public health professionals has identified some 107 areas, each of which cost the NHS around£300m-400m a year.

These are not high cost drugs for individual treatments but they are associated with particular client groups, lifestyle behaviours or common conditions.

This activity is where the bulk of local PCT spending goes, but for much of it we have little evidence of impact and there is huge variability in delivery.

We shall have to develop some new partnerships - where appropriate with commercial partners - to be supported in moving from the beautifully crafted community intervention for 30 people to an industrial scale of risk assessment, targeting, market analysis and marketing which can truly begin to tackle the entrenched inequalities which lurk throughout the communities we serve.

Stepping into this space will be a challenge for many - it's morally ambiguous, intellectually muddy, but every day there are moments of pure poetry as we do something right. It is the realm of public health management and we badly need our clinical leaders alongside us in the trenches.