Just before the parliamentary recess, we were hoping desperately for a statement on mental health. The outline version of the mental health national service framework is needed by October, and it was hard to imagine how this could be produced without a policy framework.

Instead of a formal statement, health secretary Frank Dobson outlined his plans in a letter to the chairs of the reference group preparing the national service framework, and junior health minister Paul Boateng filled in some of the details in his opening address to the group. Worth the wait? Probably, yes.

There is now a strategy for mental health. Not much surprise about the content, given the leaks to HSJ and the BBC. Ignoring the rhetoric about community care failing (what community care?, what failure?), the statement offers a sound vision of services which can offer greater support to patients and safety to the public. It makes heavy reference to the three Ss: safe, sound, supportive.

The vision is to be achieved by setting up crisis and assertive outreach teams, more acute beds and support accommodation, and more counselling services. Partnerships across agencies are predictably central, and staff training and support have been given priority status. The Mental Health Act will be reviewed, with community treatment orders a serious option. Major resources are promised, although the precise figures will only be announced in the autumn. The pledge is to deliver a greater increase than anyone has seen in their professional lives. That's one for health economist Alan Maynard to pick over.

This is a model of comprehensive mental healthcare with something for everyone. It is pragmatic and at least partially evidence-based, and aims to reassure a fearful public, service users and the workforce. It addresses the NHS, local government and the independent sector. In truth, it offers a good description of what community services should look like. But its comprehensive ambition and broad appeal may also prove to be its Achilles' heel. Expectations are phenomenal. Everyone will be fighting to extract maximum value from the element of the strategy which particularly interests them. It never ceases to amaze me how many different pressure groups have slightly different agendas in mental health, each fighting their own corner.

Realism is crucial. I can foresee a sense of deep disappointment if the spending announcement delivers less than the widely heralded 500m a year - and that's a minimum expectation.

The next possible crisis point is that more money does not automatically produce safe, sound and supportive services all around the UK. How will the government respond as new incidents in the community (or in inpatient settings) occur?

This is the crucial issue. We can throw money at a problem and achieve little: think of US healthcare. The foundations and the planning have to be there - and the intervention purchased must have the potential to deliver the desired results.

Take human resources. I fully support crisis and assertive outreach teams, preferably concentrated in areas of high deprivation. Conservatively, we will need 100 teams with a total workforce of around 1,500. This work is notoriously demanding, and well-trained and strongly supported staff are essential if we value effectiveness and sustainability. At present, neither the staff numbers, skills, training capacity, nor local leadership are there. They can be built up, but this needs time.

And take service development. If anyone believes it is hard to set up and run a standard mental health service with its emphasis on beds, try a service sensitive to local needs and cultural diversity, which meshes well across the many different teams, support services and agencies. The local expertise is not there at present, and why should it be? A long- term planning and implementation exercise needs to start now.

Training and service development cannot be considered in isolation. If managed successfully, teams will reduce admissions, and staff on hospital wards will have to look after a concentrated group of very disturbed people. Many good staff will have moved to community teams. So the danger is that wards will be run by bank staff and community rejects - if any want to work in this environment. The need for incentives, training and continuing development is clear.

None of this will be achieved by simply pointing to the issues and telling people to get on with it. The challenges are clear, but responsibility needs coupling with targeted support. The interface between national direction and local planning has so far been blurred. It is unrealistic to delegate service planning to health authorities or primary care groups. Equally, most local training consortia will not have the vision or expertise to calibrate the workforce skill-mix, identify the required competencies and commission precisely targeted packages of quality-assured training. Current guidance on this is enigmatic, to put it tactfully. Central and regional expertise will be required to support local implementation. It is unclear how this will be delivered.

This agenda is a pressing one. The production of the service framework will fire the starting pistol. Commitment from the field is strong at present, but will need to be sustained for many years. The challenges will evolve, and the development and training agendas will need to evolve too. Sustained and in-depth central support will be required to deliver the vision.

I suggest a fourth 'S' to add to the other three - 'sustainable'. Government must invest in expertise locally, regionally and centrally, if the new vision is to endure. The intention is certainly there and we will know in the next few weeks whether it will be acted on.

'The government's model of mental healthcare has something for everyone... But its comprehensive ambition and broad appeal may be its Achilles' heel'