The title pretty much tells it all: the book is a reprint of a U.S. War Department guide intended for U.S. soldiers on their way to or stationed in the U.K. in 1942. It's said to be a rather charming read.
Apparently, the book did quite well during the holiday season, and so it seems to be getting a wider release.
Here in the U.S. the book is available from the University of Chicago Press.
Update - September 3, 2005: I recently bought and read the book. It's about thirty (very short) pages long. I recommend it. As advertised, it's genuinely charming.