For those unfamiliar with William Wesley, here is probably the most in-depth anybody has gotten:

I don't really know all too much about him, I would guess you UK guys probably know more. I don't really buy the rumors that he is basically a super-powerful drug-dealer/pimp/bookie to the stars, but without any definitive word on what he actually does, that speculation will continue. I'd guess he's more of a PR guru, a 'master of discretion,' but that's pure speculation as well.