For reasons that I have not yet managed to track down, messages that I
intend to post to other groups using Mozilla Thunderbird on Ubuntu Linux
sometimes get posted to alt.books.pratchett instead. The only clue I
have so far is that these messages only get misdirected to
alt.books.pratchett, and not to any other group, and that a.b.p is the
last newsgroup in the list of newsgroups that I'm subscribed to (which
isn't in any particular order).