Rolling Stone has an absolutely brilliant piece on what they call Wall St's 'coup d'etat', which I can't recommend enough as a primer on the credit crunch.
It names the meltdown's 'patient zero' (think 'typhoid Mary') as one Joseph Cassano of AIG. He operated out of - wait for it - London! And was enabled by weak UK/EU regulation.
Seriously, a must read,
All new content on my restarted blog is here