A gamble on the former white elephant of the Millennium Dome secured Matthew Key the promotion of his career.

The steely 44-year-old, who will take over from Peter Erskine as chief executive and chairman of O2 Europe, saw huge potential for the mobile group’s brand in sponsoring the centre.

That bet paid off and saw the young executive handed responsibility for another huge deal: securing the rights to market the Apple iPhone in the UK.

Despite fierce competition, Mr Key won the contract and was rewarded when, earlier this month, he stood alongside Steve Jobs, the Apple chief executive, to announce the coup. He was also instrumental in the creation of Tesco Mobile, the joint venture between O2 and the supermarket giant.

Mr Key, who is married with three children, joined O2 UK in February 2002 as chief financial officer. He took over as head of the UK mobile business two years ago.

He joined O2 from its arch rival Vodafone, where he had worked within the retail and network divisions before becoming finance director of the UK business.

Like Mr Erskine, he amassed experience at a series of consumer brands, including Coca-Cola and Cadbury Schweppes. Mr Key, who lives near Beaconsfield, Buckinghamshire, also shares with Mr Erskine a love of football and is an ardent Chelsea fan.

Under his tenure, O2 UK has continued its inexorable rise, seeing off scepticism about its ability to thrive under Spanish ownership following its sale to Telefónica two years ago.

The business is now Britain’s largest operator by revenue share as well as customer numbers.

Mr Key’s new job will see him take on responsibility for Germany, Ireland, the Czech Republic and Slovakia, as well as Britain. A replacement for his role as chief executive of the UK business will be announced within the next couple of weeks.