A clutch of City firms have landed roles advising on 3 Mobile's £250m claim against four rival mobile phone operators, in one of the largest competition actions to hit the UK courts.

Barlow Lyde & Gilbert is advising 3 on its claim against rival operators O2, Vodafone and Orange, respectively advised by Ashurst, Herbert Smith and Field Fisher Waterhouse.

T-Mobile was also named in the case – which began under Mr Justice David Steel in the Commercial Court earlier this week (4 December) – and is being advised by Bristows.

3 alleges that its rivals abused their majority in the Operating Steering Group – a self-regulatory body that works alongside OFCOM – by voting in 2005 to retain a five-day handover period for customers wishing to keep the same phone number when switching to a new network provider. The number porting system in the European Union allows customers who change networks to have their numbers transferred within hours.

Senior Barlows disputes partner Clare Canning, who is set to leave the firm for Mayer Brown next year, was instructed by 3 in May. Brick Court Chambers heavyweight Jonathan Sumption QC is acting as counsel.

Fellow Brick Court silks Charles Hollander, Nicholas Green and James Flynn are acting as counsel to T-Mobile, O2 and Orange respectively, while Essex Court Chambers' Joe Smouha QC is counsel to Vodafone.

The case continues.

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