Diary: Bidders get more than they bargained for at Arsenal

Investing in art is a tricky business, but M&C Saatchi's David Kershaw clearly thinks he's got an eye for a masterpiece after splashing out £16,000 on a portrait of Arsene Wenger, at an Arsenal Football Club charity auction.

The M&C Saatchi partner was obviously not going to be swayed by the club's lack of silverware this season, and was eager to get his hands on "The Professor".

But this will be no ordinary portrait as the artwork will be daubed by Rolling Stone Ronnie Wood. Kershaw even gets the chance to witness its creation. For Kershaw's sake, Diary hopes Wood doesn't take a life-drawing approach.

The auction was riddled with adland connections, having been organised by Johnny Hornby and his wife Claire, who helped the Gunners raise £280,000 for charity.

While Mrs Hornby organised and hosted the glitzy do for Arsenal's Charity of the Season, Treehouse (a national charity for autism education that was set up by Nick Hornby, Johnny's novelist brother) Johnny stuck his hand in his pocket for a double charitable offering.

The ad man, clearly eager to show brotherly love, shelled out £4,000 for a lunch with his own sibling. Best order the lobster then, Johnny.

The prizes weren't the only draw on the night, though, as the entire Arsenal first team (even the ones who look certain to leave in the summer) and Wenger came to give their support and hard cash.