Introducing the latest proposals for the next stage review last month, Lord Darzi said: 'The nature of healthcare means services will always need to change, and sometimes that means reorganising how services are provided.'

While this view is easy to agree with in principle, it can be fiendishly difficult to put into practice when change is about decommissioning services that some people value but that are not offering the best value to all those who need them.

Debates of this kind have often focused on popular district general hospitals. They are now looking at primary care as well. Less widely discussed, but no less contentious, are NHS day and vocational services. The experience we have of recommissioning these types of services could offer some of the answers for the rest of the NHS as it seeks to implement Darzi's far-reaching reforms.

Patient involvement

In his latest document, Lord Darzi made five pledges about the way the next set of reforms would be handled. The first two - that changes will "benefit patients" and "be clinically driven" - aim to reassure those who fear that change is more about saving money than improving services.

The others, however, present more substantial challenges for commissioners. They state that change will be "locally led" and that "you (i.e. the public) will be involved". Taken together, these statements imply a level of public and service user involvement that commissioning in the NHS has rarely achieved.

Some PCTs, however, have shown what can be achieved in this regard. In Surrey, for example, PCTs worked with local authority commissioners to make overarching changes to their day and vocational services. The involvement of people who use mental health services was fundamental to the process.

This meant not just consulting them on plans that had been formulated in advance but involving them in steering groups, in setting out what kind of services they would like, in evaluating how well existing services met their needs and in selecting providers to deliver these services in the future.

New services

The fifth of Darzi's pledges was that existing services will not be withdrawn until new and better services are available. This reflects a long-running concern about existing services being closed down before their replacements appear.

This too has been a major concern in the modernisation of day and vocational services, where the replacement of traditional centres with a range of support to access employment and to participate in local communities has caused great anxiety for those who fear having no service at all during the transition.

The scale of the challenge with day and vocational services is considerable. Less than one-fifth of working age people with severe and enduring mental health problems are in employment, yet three-quarters would like to be. This is social exclusion on a vast scale.

Day and vocational services for this group cost£153m a year but are more likely to segregate and shelter people from mainstream society than to help them to achieve their hopes or meet their potential.

This gives commissioners a serious dilemma. How can we reconfigure current investment in order to change services that are not meeting the diverse needs of the populations they serve and that are not, in the main, based on the best evidence?

Ensuring success

Darzi's five pledges offer a starting point for the way major change can be achieved in the NHS. Commissioners in some parts of the country have demonstrated that change can happen but that the process can be long and complex. It takes perseverance and the ability consistently to involve and inform all those who have a stake in both the new and the old services. It can mean closing down underperforming services and renewing those with the potential to do better. And it needs a commitment that people will not be left adrift by change.

If world class commissioning has any meaning, it must surely be about ensuring the NHS gives people the support they need to lead fulfilling lives in the best possible health. It must be about listening to the views of the people services exist to support and respecting their knowledge of what they need within the evidence of what gives the best value for public money.

None of this is easy but it must be done and it will make people's lives better.

About Time is now available from the Sainsbury Centre for Mental Health at www.scmh.org.uk, price£25.