The biggest ever slice of the NHS is up for grabs in Cambridgeshire. Ten bidders, including NHS hospital trusts and private companies Serco, Virgin Care and Circle, are competing for a five year contract to run older peoples' services. It will be worth a minimum of £700,000. The successful bidder will provide everything from podiatry and occupational therapy to dementia treatment and end of life care. The stakes are high. But how much will patients be told about how the bid was won? With commissioners advertising dozens of other big money tenders, File on 4 looks at the secrecy surrounding NHS contracts when they're awarded and when they're challenged. Does commercial confidentiality make public accountability impossible? And how far does the competitive market improve healthcare for patients? Reporter Jane Deith Producer Ian Muir-Cochrane.