I know from experience that plenty of Scientology snailmail spam gets bombarded at people in the UK too. Constantly, whether they want it or not. (This was a few years ago, though: I have no recent knowledge, thank God).

Maybe some local Org or other got ahold of the Deering customer list, or were given it? This has certainly happened in Britain in other non-banjo-related situations. All anyone needs is an address.