Jeremy Laurance: Why more choice doesn't always mean a fairer NHS

Suppose you need an operation on a dodgy hip or a varicose vein. You have a choice: go to your local NHS hospital or to a private treatment centre, where your treatment will be paid for by the NHS. Which do you choose? Why, the privately run centre, of course. For more than a decade we have known that, broadly speaking, surgeons who carry out the most operations are the safest. If you concentrate the same procedure in a single unit you get better results.

Now a study by the Royal College of Surgeons (RCS) has found patients who had hernia surgery in NHS hospitals were 40 per cent more likely to report a poor operation than those treated in the private units. This goes to the heart of Andrew Lansley's NHS bill. Here is competition at work – and it has undoubtedly strengthened the NHS by concentrating minds among die-hard consultants who had been content to see their waiting lists grow. They were forced to respond and waiting lists have since fallen.

But the private units have also weakened the NHS. A senior ophthalmic surgeon explained to me how. Cataract surgery is among the commonest operations performed on the NHS. He used to supervise hundreds of operations performed by trainees at his hospital. Now these have been savagely cut as much of the surgery has been diverted to the local private unit. Result: a serious problem with the training of the next generation.

The private units, RCS researchers noted, were taking younger, more affluent patients with less complex health needs – cherry-picking, in other words – and this could account for their better performance. Lord Howe, health minister, while insisting that "more choice must be a priority for a modern NHS" pledged that parliament would prevent cherry-picking to ensure a "fair playing field". But he did not mention training. And this shows how difficult maintaining fairness will be. The NHS exists to provide universal care, not discrete packages to different groups. The social contract on which it is founded requires us to accept certain restrictions, in order to maintain that universality. But it is this very social contract that is now under threat from the Government's determination to break it up.