Ashurst and Osborne Clarke have taken lead roles on the demerger of Carphone Warehouse.

Carphone Warehouse, Europe's biggest mobile phone retailer, announced details last month of how it is to split its TalkTalk fixed line voice and broadband business away from its retail arm to create two new holding companies.

Osborne Clarke is acting for regular client Carphone Warehouse on the split, with head of corporate Adrian Bott and fellow corporate partner Jon King at the helm. They are working closely with an in-house team headed up by general counsel Tim Morris.

Bott has a longstanding relationship with Carphone Warehouse dating back to his time as a partner at Olswang. He has previously advised on deals including its 2006 joint venture with AOL and 2008′s $1.1bn (£703,000) tie-up with US electronics retailer Best Buy.

Ashurst is advising UBS and Credit Suisse as joint financial advisers on both the demerger and the plans to list both companies on the stock exchange by late March.

Corporate partner Steven Fox, who is leading the City firm's team, said: "The increased importance of investment banks to us across all practice areas, and the focus on them as a client class both at a corporate level and on the business side by individual partners and teams, has resulted in some excellent corporate finance bank mandates."

Freshfields Bruckhaus Deringer, Allen & Overy and DLA Piper have also won roles in relation to a related £1bn refinancing for the two companies. A&O advised ING and RBS as arranger and lender in relation to the facility for Carphone Warehouse and TalkTalk respectively, while Freshfields fielded a team advising Carphone Warehouse and TalkTalk on the debt restructuring of both companies. DLA Piper advised a syndicate of banks including Barclays on TalkTalk's debt.