Mmmmm.  Just had an additional thought.   Could this BSA barrel have been intended for the rebarrelling of a 297/230 Greener Cadet, again in 1907?   If so, then it makes me wonder the reason for having the same barrel threads as the Francotte?  Did Francotte (later BSA) and Greener make the Cadet actions to their own individual design and get their barrels from another (such as BSA) all of the same thread?     Did the Commonwealth rebarrel both their Francotte and Greener 297/230s for the younger cadets using BSA barrels?
Now my head is starting to hurt.

Peter.