Struggling Williams' sale of stake was 10%

The Williams Formula One team has revealed it sold a 10% stake in the company to Austrian rally driver and motorsport entrepreneur Christian Wolff.

While it was known that Wolff had made an investment in the business, the size of his stake has come to light in company filings today.

It is believed Wolff paid £10 million for his stake and it sits alongside his other investments including shares in driver management firm Aces Management and German company HWA, which supplies engines to the Formula 3 racing series. Boss Sir Frank Williams founded the eponymous team in 1977 with engineer Patrick Head. Since then the Oxfordshire-based outfit has won seven F1 championships.

However, it is now one of the few teams in F1 not owned by a billionaire or a car manufacturer and it has failed to match the pace of its rivals.

Williams has not won a race since 2004 and lies seventh in the standings. Over the past five years it has made combined after-tax losses of £5.9 million and last year Williams said he agreed to sell "to take care of some other needs and pay a few bills - my mortgage, for example".

The sale diluted Williams' 70% stake in the team to 63% with Head's share falling to 27%.

It came at just the right time. Williams' pre-tax profits fell by 50% to £4.5 million in 2009 as revenue reversed 13.8% to £108.3 million on losing sponsorship from bankrupt Icelandic conglomerate Baugur. It used its profits to pay down debt and finished the year with cash of £3.9 million compared with net debt of £25.5 million at the end of 2008.