Mobile phone company Vodafone smashed City expectations by posting a 41 per cent increase in underlying pre-tax profits for the first half of the year, with a little help from David Beckham.

Chief executive Sir Christopher Gent said margins and turnover were up across the business with more revenue coming from text and data services.

Pre-tax profits soared to £4.25bn in the six months to September 30 before one-off costs, up from £3.01bn last year. Vodafone said extra advertising costs and the launch of 3G services in Japan meant the second half performance would be weaker.

But Sir Christopher said the group remained ''very confident'' in the future prospects for the business.

Turnover in the first half increased 67 per cent to nearly £15bn on the back of higher usage levels and rising average revenue per subscriber.

The key average revenue measure - ARPU - is now running at £282 a year in the UK compared with £276 in March. More lucrative non-voice services such as text messaging now account for 13.2 per cent of service revenues worldwide, up from 11.1 per cent.

Mobile phone operators have been focusing on generating more cash from existing subscribers as the market becomes more saturated.

Vodafone launched its high-profile picture-messaging service Vodafone live! last month - with the help of football star David Beckham - and has since shipped over 50,000 handsets.

Sir Christopher said: "We are doing very well, we are selling more or less everything we can get."

Vodafone has also switched more pre-pay users on to lengthier contracts and disconnected inactive customers to "clean up" its subscriber base