Why has the NHS National programme for IT failed?

A Department of Health press release says that a "review of the National Programme for IT (NPfIT) has concluded that a centralised, national approach is no longer required". But where is this review? There's no link in the press release, as one might expect. There's no explanation on the Connecting for Health website, beyond a reference to this press release.

We need to know why the programme has failed. At face value the concept of the Summary Care Records system made sense. It seemed as though money had been wasted by allowing the individual parts of the NHS to develop their own patient information systems. But then the NHS just seemed to get locked into contracts that were never delivering.

The Computer Weekly Editor's blog suggests lack of clinical involvement and changes in technology were amongst the reasons, but these do not seem a sufficient explanation to me. You can understand the government abandoning the project when so much money has been wasted. But the NPfIT has hindered Trusts developing their own hypertext linked systems, which are not that brilliant anyway, because it was always said we had to wait to see what NPfIT could produce.

Have we just all been naive and trusted people who did not really know what they were doing? The people working in the project and the developers have done alright out of it. Why was it so difficult to produce a national system that worked?