HI spot the dog! & others!
the bass on a BC can only be used as a form of ornementation & not to drive a rythm as on a DGbox. This is because playing accross the rows ther are only a limited number of instances where a boss note will harmonise with a trble at the same time. Most BCC# boxes have stradella (accordion) bass which will provide harmony and rhythm as requireds.

Yes Sir Jimmy Shand played BCC# because he invented the bugger. Starting on single row 10 key melodeon he progressed via 2 row & then a hohner organola 36 bass 2 row ( on which his early recordings were made) the 3 row coming in about 1936 as the Shand Special which in turn developed into the famous Shan Morino after the war.

If it is any help to anybody I am in merseyside?westLancs and teach melodeon and button accordion i.e. DG, BC & BCC# & also continental chromatic up to intermediate level.
If anyone has any specific problems I will try to answer them.