Earlier this year, just a few months after Austrian rally driver Christian Wolff bought a stake in the company which runs the Williams F1 team, Pitpass remarked that "the details of Wolff's share will be revealed when its next annual return is filed." That time has come and the result shows just how much of a minority shareholder Wolff is.

Writing in the Evening Standard, Pitpass' business editor Chris Sylt reveals that Wolff owns just 10% of the team with its founders Sir Frank Williams and Patrick Head holding 63% and 27% respectively. The sale to Wolff took place nearly a year ago in November 2009 but, strangely, the size of Wolff's stake was not announced at the time.

"I don't want to go into too many details because our new partner is a fairly conservative-minded businessman," said Williams at the time of the sale. Wolff would only confirm that his stake in Williams is "between 10 and 49%," and the team's annual return has now confirmed that in fact his shareholding is right at the bottom of this range.

It is believed that Wolff paid £10m 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.

Despite the sale Williams is still one of the few teams in F1 which is 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 this year's standings with only three races remaining until the end of the season. Over the past five years it has made combined after-tax losses of £5.9m and last year Frank Williams said he agreed to sell "to take care of some other needs and pay a few bills - my mortgage, for example." It came at just the right time.

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

However, this position is expected to worsen because £14.6m of the income Williams received last year was attributable to 2010. It is also set to lose an estimated £11m of sponsorship at the end of this year when the Royal Bank of Scotland puts the brakes on its sponsorship of the team.