Thanks for the replies, everyone. I haven't been back to the pic since I posted here last, but I'll take a stab at it again with your suggestions as soon as I get a chance.
EDIT: I'm done, I guess. There could be more done to it, but, well, I don't want to do any more!
Here's a link to the before and after versions, because although it's not a big image file, 100kb doesn't really show much.
It's the second photo I've ever restored, and the first colour one.