GP leaders believe that this could more than double to 10% by 2014 because PCT-run practices are becoming available and singlehanders are being forced out due to NHS reforms and cuts to pensions.
Interestingly the NHS is far less receptive to private companies in Scotland, Wales and Northern Ireland.
Our analysis on page 19 (Should GPs fear rise of private firms? - GP, September 23) takes a look at the investigation findings, and asks what they mean for GPs and whether they should fear the rise of private companies.
Indeed the coalition government might argue that GPs as independent contractors are little different to private companies.
But different they are in many ways and that should be a starting point for debate.
RCGP chairwoman Dr Clare Gerada, a partner in an NHS organisation bidding to run GP practices, argues that it focuses on 'dealing with patients nobody wants ... we go into the hardest areas of London and focus on transformational change' and 'we are part of the community'.
GPC deputy chairman Dr Richard Vautrey echoes the focus on community, saying: 'You face your patients in local supermarkets as well as in your surgery. With larger organisations, management is more remote.'
However, Care UK says it offers flexibilities to experience a number of different working environments.
GPs have more tools than they might think to protect traditional general practice. These include merging or federating to prevent singlehanded practices being taken over by private companies.
Retiring GPs might also want to consider ensuring succession as they depart their practices. Equally, there is a debate to be had with younger GPs about why traditional general practice should keep private companies at bay.
If traditional general practice is to continue, partners must do all they can to provide the opportunities for younger GPs to enable this continuity of care.