It wasn't so much Hamlet without the prince as Hamlet without the theatre. When ministers last week proudly lifted the curtain on the new consumer-choice NHS, the centrepiece of Tony Blair's public service reforms, the IT supposed to make it all work was down.

Officials admitted this week to a "significant interruption" in the system supposed to allow NHS patients to choose where they want specialist treatment and to book their appointment from their GP's surgery. Problems caused by a major software upgrade caused intermittent problems to the "choose and book" service for six days. Thus on January 2, when Patricia Hewitt, the health secretary, unveiled the new choice-centred NHS in England, the system was unavailable nearly all day.

While downtime is hardly unusual in big new IT systems, this is an embarrassment to the NHS National Programme for IT, the world's largest civil IT programme. The system at fault was not the booking software as such, but in the underlying digital "spine" supposed to connect all parts of the NHS in England. Officials had previously boasted that the spine would be available 99.8% of the time, with recovery within 30 minutes of any crash. The NHS's apparent inability to achieve this, despite massive funding and the efforts of a highly experienced project team, does not bode well for other government IT schemes such as the identity card.

The NHS compares the spine to "a single, big electronic telephone exchange", routing patients' information securely. In fact, the spine is much more than this: it is supposed to carry summary health records of all NHS patients in England for use in medical emergencies. The spine also controls access to NHS systems as well as providing a central resource of "demographic" data about patients: names, NHS numbers, addresses and dates of birth. This is essential for doctors to be certain that information from an NHS system applies to the patient sitting in front of them.

This database, known as the patient demographics service, appears to be the source of the spine's downtime. The problems arose from "application misbehaviour" - a grief familiar to PC owners who upgrade a key piece of software and find that another application no longer works.

Down graded

The trouble began on December 18 with the installation of a major upgrade of the spine software. This included what should be the definitive, "strategic" version of the personal demographics service, replacing an interim system.

The new software reacted badly with one of the many different systems used by GPs to manage their practices, and generated spurious messages that overwhelmed networks and servers. This rogue behaviour masked other incompatabilities between the new demographics service and the "choose and book" software. "We were into Christmas before we were able to start diagnosing," said one of the team who worked over the holiday to resolve it.

The failure raises questions about whether any system as complex as the spine can be tested fully before implementation. Connecting for Health, the agency responsible for the NHS programme, admits that it wasn't.

It also raises the question of whether the whole new NHS is vulnerable to a single point of failure.

The spine is the responsibility of BT, which in December 2003 beat IBM to a 10-year contract worth £620m to build and run the system. It is based on an Oracle database running on distributed Sun servers, an architecture "not dissimilar" to that of eBay, a source close to the project says. Last year, in response to worries about resilience, the system was adapted to "fail to local" so that NHS organisations could continue to function without the spine. This is what happened over Christmas and the new year - as relatively few doctors are using the new software, its non availability had little impact on patients.

When the NHS starts using the system in earnest, however, there will be less tolerance for failure. Sources close to the NHS IT agency Connecting for Health said that the Christmas upgrade was a one-off event. "We were unlucky." The hope is that, with the infrastructure now installed, there will be no more need for fundamental upgrades and the service will stabilise.

Not everyone in the NHS is so confident. Professionals reading the web news service e-Health Insider, called for a fundamental rethink. "The whole system should be taken offline whilst these problems are rectified," said one. Some began to question the whole system: "if the failure of spine functionality had no adverse impact on patient care, just what clinical benefit was it adding when up and running?" To which another responded, "It's like a bank saying outage of their ATMs had no effect on customer balances."

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