In my time playing, I've come across two different 26 button wooden ended Jeffries in C/G. In both cases, the owners loved them, and I was very impressed with the sound. I'm well set for my C/G concertina, but I've been lusting after a Bb/F and an A/E (or Ab/Eb) for quite some time.
Has anyone ever come across one of those older 26 button wooden Jeffries boxes in Bb/F? I've never seen one myself, maybe they don't exist. But if they are out there, I will be on the hunt! I've heard of one in Ab/Eb (Greg Jowaisas had one) but wasn't looking at the time.