Well, you weren't wrong. It was tough, mine had been glued together

Anyway, I though I'd stick up a few pics as I failed to find any (and even remembered to take some while I was doing it

) when I was looking for confirmation I wasn't being a k-nob.
So it comes apart (eventually, after much cursing and scoring with a scalpel and prizing with a screwdriver) like this
Now I suspect Honda didn't want this to be user serviceable/weren't expecting it would need it. The pins of the cells are soldered to the board
So a quick whiz with the soldering iron and de-soldering gun and we have separate board and cells.
The cells are Panasonic VL1220/1FC, but that tab configuration seems tricky to get hold of. RS stock them with straight tabs so it may be a case of a little modification.
Anyway hopefully this might proof useful to somebody. I'll try and remember to update it if I make any more progress.
Joe.