Outer Oil Excluding Band on N Clutch Sprocket

Tim, I have just recently worked on the clutch of my 1956 ES2 and it doesn't have it.

I can't say whether or not a previous owner removed it or not, but it works without it. 

Don Anson
Melbourne 

I have read in one of the 50's Handbooks that the band was innefective and uneccessary.

How did the band know if it was meant to be keeping oil in or out of the clutch?

I got sick of it coming loose, so I threw it away about 50 years ago without any ill effects!
John
 

I suspect that the fact that Norton deleted it tells us everything.  But they did claim that new friction materials (rather than cork) were oil resistant.
The rubber sealed chaincase was only from 1935.  Did they have the steek ring before that?
The WD manual describes it as "clutch plate cover" 

My Model 50 had one. When I renewed the clutch sprocket (thus outer basket) the band couldn't go on again, as the fit was now very loose around the new basket.

This disturbed me, but after some research as described above, I felt safe to leave it. It didn't give negative effects. To be honest, I suspect that any stray oil can now be flung off more effectively.

I've used it for a couple of years that way without any problems. Last year, I remembered that motorcycle engine oil has additives to prevent clutch slip. That's why you can't use general car oil, as it makes the plates stick and slip. So I made a point of topping off the primary case with modern 10W40 motorcycle engine oil, just for the sake of it. It might put your mind at ease.