Bingo 3... Alight tap with a punch and small hammer on each of the cut outs in turn and the lock ring was loosened - It is a right hand thread.

Bingo 4... As you say with the cover off ..... all becomes obvious !

Bearing is marked on outer "England", "SKF",  "K-1130N1" and on the inner "T-201807"

I cannot find any references to this bearing anywhere on the web, including A-N

The part number in the list given in my post 35 above is 01.4868 again no references to be found

The bearing looks to be a tapered roller and in good condition so hopefully I won't need to replace it.

BUT the inner does not seem to "pop" out of the outer.

Any clues to getting the inner out gratefully accepted !

Thanks