Seems like you have a choice, coming from the States. We HAD TO use a shipping agent; the DEFRA-approved carriers from Japan demanded it. (BA is not an approved carrier, btw. Odd, isn't it?)
They didn't do any of the paperwork, but they checked it. For about 2 grand. I had already faxed everything over to DEFRA and confirmed it was fine.
Bah, shipping agents.