Jon says, “This is such a lovely song. I keep meaning to learn some more Brecht stuff, so this is a start anyway.”
I must confess that Brecht is another I know little about. Mainly Norfolk has Jon’s source for this, Martin Cartthy’s notes, which refer to a Brecht play called The Good Soldier Schwejk. I couldn’t find that listed amongst his plays as listed here on Wiki, although that title actually belongs to a book by Jaroslav Hašek. It follows the fortunes of the titular soldier through WW1 as a recruit in the Austro-Hungarian army. It seems Kurt Weill turned Brecht’s text into a song and if you scroll down towards the bottom of this Wiki page you’ll see it listed with a date of 1942. I don’t know whether the arrangement Martin heard is based on Weill’s version, but I suspect it was, either way he recorded this twice, once solo and once when he rejoined Steeleye Span. There’s also a very good version of this by PJ Harvey and you’ll find a simple but effective video for that on YouTube easily enough, if you fancy it. It seems to have pretty much the same tune and Marianne Faithful has also recorded it as The Ballad Of The Soldier’s Wife and that’s rather splendid too. I think this version works well unaccompanied too.