He's one of those people who are famous for...erm...being famous. Having no discernible talent of their own, even in the looks department, they acquire fame or infamy due to who they are married to/divorced from/sleeping with/friends with. Paris Hilton is another obvious example.
Then they raise their profile further through appearing on I Used To Be A Celebrity For About A Week Back In The Nineties By Making Dreadful Pop Records And Now The Money's Running Out, Get Me Out Of Here But Not Until I've Had The Chance To Get Off With A Famous Topless Model And My Agent's Booked Hello Magazine For The Wedding Photoshoot. Or in David Guest's case, I've Never Been A Celebrity And I'm Distinctly Odd, But I'm Good Buddies With Michael Jackson, Leave Me In Here Until My Face And Name Is Indelibly Etched On The Consciousnesses Of The British Public.
Rant, as wallis1007 so perfectly puts it, over.