What I've learnt over the years, is that most, if not ALL the big, medium and small names in gun making, out sourced parts/jobs/complete rifles/shotguns in their time, whether in good or bad times and branded them as their own.
Birmingham and London had lots of different parts makers who supplied the big names.
I would assume that wealthy clients of Rigby/Holland/Purdy/etc, would have a big input as to the outcome of their chosen rifle/shotgun. We are just seeing the results of those orders.

Course language aside, this has been an informative thread.