Richard Smith, now director of the Ovations Chronic Diseases Initiative - part of UnitedHealth's US operation - said the firm was bidding to run 90 practices. It currently runs six of the 40 practices in England which are in private hands.
Mr Smith said the DoH was using the threat of the private sector to drive up quality: 'I don't think the government has a vision of 50 per cent of primary care supplied by big companies.
'It's probably something like 5 per cent. It hopes that will be enough to ginger up the rest.'
He said that UnitedHealth had seen 'very dramatic improvement' since taking over a practice in central Derbyshire. 'Patients increased by 40 per cent, quality scores increased and it is now open 8am to 8pm, with Saturday opening on the way.'
Mr Smith said that all the neighbouring practices that had previously closed their lists had now opened them.
He added that 'ultimately United does not see itself as a business taking clapped out practices and improving them'.
Instead it was considering whether there was demand from GPs to hire its technology and commissioning expertise.
However, a GP in the audience warned: 'If 5 per cent of practices are taken over by the private sector, you have to wonder if this is the beginning of the privatisation of primary care.'
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