Your news focus on health and the London mayoral candidates (Vacuum task, pages 14-15, 23 March) exposed some problems and sounded some alarm bells. It did not tell us what we really want to know: what difference will a mayor and assembly make to the health of Londoners?

All we have had so far is political flannel and statements on who would like to grab power from whom. The opportunity a mayor and assembly present for health and the health service is an extraordinary one, and Londoners will not be forgiving if it is wasted.

The link between poor housing and health is just one example of this potential: the Health of Londoners project states that every 1 per cent increase in overcrowding is associated with about 1.25 per cent increase in admissions (about 1,000 extra) across London for respiratory illness. The converse will be true.

The mayor and assembly will have legal powers to influence both health and the NHS, albeit obliquely. There is already a network of statutory bodies with power to influence London's NHS: the 29 London community health councils and London Health Link, their umbrella body. Our role is to develop an impartial pan-London view, grounded in the patients' perspective. London CHCs will see at first hand the difference between London premayor and London post-mayor.

Modernisation, the polite term for making the NHS and other public services get their act together, is just change for its own sake unless it leads to services the public need, delivered in the way they want. That is not just about politics or management - it is about tangible results. We need to know what those results will be.

By the way, Conservative candidate Steve Norris favours a 'watchdog service to monitor bad practice and provide information to patients'. Well, here we are and we are delighted to have his support.

Elizabeth Manero Chair London Health Link