Just to let you know I've managed to remove the locking ring and extricate the remaining bearing in my D1 rear wheel hub. After heating the area next to the locking ring I tapped it (gently!) using a hammer and drift in a clockwise direction and it undid - no trouble at all! Success, at last! So, that makes it three bearings in my hub, when there should only have been two! But there does appear to be a distance piece missing from the speedo side, part no. 90-6065, so maybe some 'expert' from bygone years fitted the extra bearing to compensate. I must look into it more thoroughly, I think.
I've been the proud owner of a 1965 BSA Bantam D7 since 1991, affectionately known as Little Willie (Wilhelmina) and love to take her out for a ride so that others can see her.