Talking to GP, Nick Goodwin said if GP-led commissioning is to deliver what the DoH wants it is 'almost certain' that larger units will have to be created.
'In order to deal with the whole or most of the budget and tackle the issues, the scale of commissioning groups needs to be more substantial than in the case of fundholding,' he said.
Mr Goodwin said improving care will need 'more networked, integrated and joined up solutions,' which do not undermine the value of general practice.
He said: 'This is about reducing isolation and getting GPs to work in partnership with their colleagues. This is the next step forward for general practice.'
Mr Goodwin said the inquiry, due to conclude later this year, will offer recommendations about how to assess quality in general practice.
Practice accreditation, revalidation, updates to QOF, benchmarking through balanced scorecards and patient-reported outcome measures amounted to a 'quality revolution that is likely to challenge and change the nature' of general practice.
He said a 'more intelligent approach' to measuring quality is needed, as measures such as QOF do not 'capture the true essence of care quality'.
The King's Fund has launched an online page aimed at allowing the profession to inform the inquiry into general practice. The page can be found at: www.kingsfund.org.uk/GPinquiry