Thanks chaps – it all seems to confirm what I thought.
I must bookmark the littlemachineshop link, as my original manual (long since lost) was written in bad 'Chinglish' & didn't have anywhere near the same amount of information.
Just as an aside, there are a couple of grubscrews in the top of the saddle. First of all I thought they might have been covering lubrication points but when I removed them, the holes appeared to be blind. My only other idea is that they're fixing points for some attachment. Can anyone confirm or deny that?

Brian