well, in theory the UK government hands information over to the USA - part of the 'war on terror'. In practice, I don't know.
Normally, you just fill out the visa waiver form on the plane and they look at it when you land and let you in. You don't qualify for the waiver if you've been arrested, so you have to apply for a visa, tell them what happened, and hope they'll give you one. (They won't necessarily refuse.)
If it was me, I think I'd just get on the plane, fill out the form and hope John Reid had kept his mouth shut. But I don't know how much information actually does get passed to Washington, so I really don't know if this would work or not. It's been asked a few times under Travel and I don't think anyone has said they've been refused entry.