hey--newbie here with a newbie question--

i am trying to learn about WR doubles at the moment and am currently at this question:

of the extant westley richards doubles that are out there (vintage, new, whatever--all of them) what is the prevalence of the .476 chambering? i am somewhat aware of the cartridge's history/development....

how popular was/is it?
even though it was 'proprietary' did any other makers
ever chamber guns for it?