Accenture, the management consultancy locked in a £220 million High Court battle with British Gas, has lost an initial ruling for its role in a faulty IT system that the utility company claimed had reduced its customer billing service to a shambles.

British Gas, the UK’s biggest supplier of gas and electricity, with 12.5 million customers, welcomed the judgment, which was made in its favour on all of six issues and will pave the way for a full trial next year.

“British Gas is pleased with the judgment, as we feel it brings us one step closer to holding Accenture to account for the disruption caused to our customers,” the company said. “We look forward to moving to the full trial as soon as possible.”

Accenture said that it disagreed with the ruling and planned to appeal. In a statement, it said: “There has been no final determination of the case or any of the detailed underlying facts of this case. We remain confident that Centrica’s claim is baseless and that Accenture will prevail when the factual issues are examined in detail at trial.”

The 2006 IT project, known as Project Jupiter, was the cause of poor customer service that led to hundreds of thousands of people abandoning British Gas, according to a 2008 High Court writ. At the height of the problems, customer complaints trebled and British Gas was forced to employ 2,500 extra staff in an attempt to resolve the mess. British Gas is claiming up to £220 million in damages for costs and lost business resulting from the episode.

On Friday the High Court issued a judgment on the preliminary issues raised by Accenture, relating to the wording of a contract between the two companies and a warranty claim. The judgment from Mr Justice Field at the High Court in Winchester was in favour of British Gas on all six points.

During 2006 and 2007, British Gas was strongly criticised by consumer watchdogs over worsening standards of customer service when it was raising gas and electricity prices.

British Gas, which claims that six fundamental breaches of a contract caused a “severe adverse effect” on its business, is being represented by Jeffery Onions, QC, and Linklaters in the case; Accenture is being represented by Geoffrey Vos, QC, and Freshfields Bruckhaus Deringer.

Accenture was recently selected by the Department of Energy and Climate Change (DECC) to provide strategic consulting on introducing smart grid technology to the UK. It uses sensors and specialist IT systems to minimise energy waste and carbon emissions. The company will be responsible for analysing the grid network and will advise on adopting the technology in Britain.

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