> More importantly we're in London, England - not the West Coast :-)

That explains everything.

I had a friend who actually got turned down for a management position for wearing a suit to an interview (they thought he was "too formal" for the job). PayPal, I believe.

I rock the Silicon Valley Casual for interviews-- jeans and an untucked button-down shirt for consulting gigs (and employee-jobs that I already know I want).

If it's a really creamy consulting gig for a large company, I might even make it slacks, semi-dress shoes, and untucked button down. Regrettably I don't have the complexion for khakis, since blue button-down, brown semi-dress shoes and khaki slacks [with cell phone on a belt clip] appears to be the uniform of choice around here large boring companies that think they're casual.

For startup interviews, I will wear a funny t-shirt, often involving pirates.

You will note that I never overdress beyond these levels (for an interview), as the casual dress is part of my filter against stupid, boring companies.