Thanks guys!,
I just wondered about the history of the thing.
Battery valve sets were quite big here and in Australia and to a degree it was because of the lack of mains electricity in parts of both countries, being held back by both WW1 and WW2.
I've had the inkling to open this thing up, but the "good" side of me says, just leave it as it is.
I'm going to store it in a heavy plastic bag to make sure that it doesn't deteriorate any further.
With vents of course.
