Where Do Politicians Come From?

Marc Sidwell's latest post at City AM neatly points up the lack of worldly knowledge possessed by our current crop of politicians. However, I'm not happy with Sidwell's, proposed solution - i.e. a supply side of the economy allowed to let rip. Rather I'd like to see some sort of "experience requirement" placed upon all would be MPs. Not sure how it would work - ideas on a post card, please.