London regional director Nigel Crisp has warned the chief executives of the capital's health authorities, trusts and primary care trusts that there will be a 'very complex and very long' process to implement the NHS plan.

In a letter sent out on Tuesday, Mr Crisp said the first meeting of London's NHS plan group - held last Thursday - recognised the 'enormous effort' required to manage 'a process of major transformation'.

The group, which meets again today, has brought together one trust and HA chief executive from each of London's five Turnberg sectors so far, but expects to broaden its membership in future.

Mr Crisp said processes to develop implementation plans at trust, regional and national level would happen in parallel - with local findings feeding into national work, and vice-versa.

Speaking on Tuesday, Mr Crisp said: 'I certainly expect the trusts and HAs to be having discussions about what their part in this is over the next 10 days, ' ahead of the next progress update from regional office. 'I will be wanting to know what they have done.'

'We have got to interlock with what is happening nationally but there are some issues which are peculiar to London. There are a big set of issues around the diversity, we have got quite a poor infrastructure, staffing problems are a particular issue for us.'

Mr Crisp said implementation of the plan in London would be helped by the fact the capital had already done 'a lot of good collaboration work' with its health and mental health strategies.

He said it was 'difficult' to map out a local timetable for implementation until more detail emerged about the national timescale. Appointments to the NHS modernisation agency are expected in the next few weeks.

London plans to follow discussions at HA and sector level with an implementation meeting on 31 October.

In his letter, Mr Crisp warned that the plan would 'require us to change the way we work at the same time as hitting short-term targets'.