The Department of Health has named the 55 organisations that will spearhead its plans to hand commissioning over to GP consortia.
According to ministers, the "pathfinder" consortia will identify issues and areas of learning in the new commissioning structure, as well as testing different design concepts.
The majority of the consortia are from the North West, with 12 based in that region. There are eight from both the East of England and London.
There are only three consortia each from East Midlands, West Midlands and the North East, while only two are from Yorkshire and the Humber.
Information obtained from primary care trusts in October reveals that the organisations range in size from WyvernHealth.com in Somerset which covers 75 GP practices and a population of over 500,000, to a single practice consortium, the Red House Group Hertfordshire, which has just 18,900 patients.
Another consortium in Fleetwood, North Lancashire consists of just two practices covering around 23,000 patients.
An NHS commissioning budget of around £750 million would be needed for a population of half a million. However it still is not clear how much will be handed to consortia, as the NHS commissioning board will centralise a number of commissioning responsibilities.