Three years ago Tom Alexander, the chief executive of Orange, gave up the City in favour of a more relaxed lifestyle. The classic car enthusiast, who had just presided over the sale of a mobile phone business that he had built into a £1 billion group, said: “I’ve got cars I’ve never driven, a family I hardly ever see and a house in France I hardly ever get to visit.”

Now Mr Alexander is back in the cut and thrust of corporate mergers and acquisitions. It emerged that Orange is going head-to-head with Vodafone in the battle for T-Mobile UK, the under-performing British division of Deutsche Telekom, the German phone group. The deal under discussion is said to allow Deutsche Telekom to take advantage of any benefits from the deal, possibly by placing T-Mobile into a joint venture with Orange.

Orange is said to have costed a tie-up and identified synergy benefits of between €4 billion and €6 billion (£5.1 billion). The two companies are expected to fight it out for a deal that could be valued at £3 billion. Orange declined to comment yesterday. The group had claimed previously that no offer had been lodged.

Mr Alexander joined Orange UK in January 2008 as head of its mobile and broadband operations. His task was to reinvigorate the France Télécom-owned brand, whose halcyon days were over. Orange, once the biggest UK mobile group by number of subscribers, has slipped to third place, with 15.85 million customers, 22 per cent of the market.

Last month, to boost its rankings, the group announced a tie-up with HMV, the music chain, to open concessions in its stores. However, analysts were sceptical about how much the link could achieve. Like its peers, it is suffering from fierce price pressures within what is one of Europe’s most competitive mobile phone markets.

Mr Alexander was a salesman for Telia and Ericsson before rising through the ranks at BT Cellnet to become deputy commercial director before leaving in 1998.

In 2006 he left Virgin Mobile, which he co-founded with Sir Richard Branson in 1999, with a £6 million payout after its merger with NTL, the cable operator, now Virgin Media. Virgin Mobile is Britain’s biggest virtual mobile operator, with almost 500,000 customers. Mr Alexander has brokered several deals with virtual operators in a bid to profit from a £1 billion a year market.

Mr Alexander, 48, who is married with two children, remains a classic car collector.