Never heard of "The Club" model however I believe Slug Gun on here is doing a book on all the earlier Webley rifles so we may see something about it in that. I know I am eagerly awaiting its publication.
Of course the rifle you descibe Binners would be a 3rd series rifle and the Supertarget did not appear until much later so perhaps this is an earlier attempt by Webley to market a target version of the MK3.
I have a .22 2nd series MK3 to which I am thinking of adding a PH17B would that then confuse future collectors?