Poor leadership in NHS organisations is threatening to jeopardise Lord Darzi's vision to transform the capital's healthcare.
NHS London board papers state it is 'likely' there will be 'insufficient leadership capacity and capability in primary care trusts and allied NHS organisations' to deliver the now junior health minister's plans.
The severity of the threat has been raised from amber to red - the worst level - in the strategic health authority's latest assurance framework document, discussed at a board meeting on 26 March.
It is named as one of three "key risks" along with accident and emergency waits and "insufficient resourcing of the 2012 Olympics programme".
Lord Darzi's Healthcare for London report, published last July, outlined ambitious proposals to introduce polyclinics and centralise specialist services. Seven clinical pathway groups have been set up to focus on areas such as long-term conditions and end-of-life care.
But a senior NHS manager in the capital said: "I wonder whether the scale of the undertaking has been realised. I hope we're not going to try to do too much."
The manager questioned whether chief executives were being properly supported by NHS London.
King's Fund director of leadership Karen Lynas said the fact that London PCTs had not been reconfigured in 2006 remained "a real issue".
She said: "With a lot of comparatively small organisations, there's an issue about attracting the right level of talent."
She also warned that PCTs across the country needed to improve their skills in preparation for the final report from Lord Darzi's national review of the NHS, due in June. "All PCTs are facing similar challenges in that they have got to skill up a different calibre of leader and take on big provider units and address the Darzi recommendations."
Robert Creighton, Ealing PCT chief executive and chairman of the London PCTs board, said: "It isn't easy to attract the best people if pay is considerably below that of foundation trusts and local government."
An NHS London spokesman said it was working closely with PCTs to ensure they had sufficient leadership capacity to take on the Darzi proposals. He said: "It's such a massive project that when we look at everything included in Healthcare for London and the changes that could happen, it would be unreasonable to expect PCTs to be ready for it straight away."
The risk assessment had been increased to red because the SHA had closed its consultation last month and was clearer which proposals would be developed, he added.
In a further blow to the capital's health managers, fears were also raised over the delivery of a "health legacy" - a key commitment in the London bid for the 2012 Olympics.
NHS London was charged with overseeing initiatives to improve Londoners' health. But the board papers reveal that 2012 governance structures there are "not fit for purpose" and resources are "inadequate".
Former medical adviser to London 2012 Peter Hamlyn said it appeared no one was taking responsibility for the health legacy. He said: "I'm very fearful that the reason we got the games is actually not going to materialise. I find that rather shocking."
The concerns were echoed by the public accounts committee, which claimed the current budget "cannot be reconciled" with commitments in the original bid. The Department for Media Culture and Sport, speaking on behalf of the Department of Health, said a report on the legacy was due in the next two months.
NHS London public health director Simon Tanner said: "Our 2012 health group had the wrong people in it." This was being changed to "ensure clarity between the role of the SHA and the DH", he said. The finance problems were about "staffing and project management" and were being addressed by carrying over money from last year's budget.