I haven't been able to find anything to confirm it, but I suspect the Broom Brigade idea helped feminist/suffragette movements get rolling.

The brooms would have made the women seem harmless and non-threatening..sort of cute..and since the brigades appear to have started as an insistence on equality, it seems natural that like-minded women would have been attracted to the idea.
The progression from broom drills to more openly political goals seems logical.