Bill Hurlow popped to mind for me, too, but I decided there was not enough in the OP's example to make it a good match. Hurlow certainly did use a plain full-sloping crown along with very ornate lugs, and some had no headbadge holes (used head decals instead) but...the extremely high quality he generally exhibited is not present in these lugs, IMO.
Of course he built for so many others as contractor, (Holdsworth Shop, Freddie Grubb, Claud Butler, Mal Rees, and Condor) I'm sure he made plenty that were not the gleaming jewels he built under his own brand.
But I wonder if "RB" could have been an apprentice to him, in one of those contact shop deals?