Ian -
Just found this thread through a Google search for "Ritson +grocer" (thank God for Google!), and have now joined up to RootsChat.
Don't do anything else...and certainly don't buy any BDM certs....until we have talked at length. I have masses of info, certificates, census entries, etc, for the Barnes family you are interested in, and their forbears back into the C18th.
We are in fact a perfect research match - I've already done loads of work going back, and I was just beginning to move forwards in time to try and trace any descendants of Hunter & Miriam Ritson ....who would be my cousins, as my mother's mother was Miriam Barnes's sister, Edith.
Anyway, I'll stop nattering on the open forum, it could get boring for others. Lets get in touch by PM?
Ossie