I'm removing a few bits to get coated or chromed, the lower sprocket cover has no screws in it (it should have, but the prior owner doesn't seem to have bothered) and only seems to be held on in two places that I can see.

1. By the gear change shaft which comes through it via a surrounding rubber seal

2. Possibly, by a bolt/spring clip retainer thing, behind a rubber bung/cap. Although I've removed the rubber bung, undone the hex nut that allows me to remove a small 1" long grub screw and then I've bent in the ears of a retaining clip.

The damm thing won't come off though. Any advice would be appreciated.

Jiggle it ... use a claw hammer, using the claw to lever it free. It's held on by bolts the gear change and 2 dowels but they are tight.

Thanks Evil, I'll give it some tomorrow night. Out of interest, do you know what that odd spring clip fitment is for behind the rubber cap?

There is an adjuster for the clutch pushrod mechanism behind the rubber grommet, so its probably something to do with that.
A few good belts from a rubber mallet will have the cover off in no time.

Yup it's the clutch adjustment, bet you get it to tight when you put it back together :D

Thanks all, as you said, a few belts with the mallet and some brut force and it's off. The down side is, it looks like a rainy day at Glastonbury behind the cover. Excuse the french, but what a shit pit. That's going to take a few hours to degrease.