Harry Cox of Exeter who rode a Brough SS80 & Blacknal side car from 1939 till 1990, born 1898, also had three "A" Rapide's along with a host of other exotica but all outfits had hand brakes in a form so simple and worked well, a fine tapered piece of hardwood with a hole to attach a lanyard to, simply wedged it into lever between cable and pivot point.
may be not as aesthetically pleasing as a BSA winged wheel model but did cause amusement at rallies. I have one on my rotorvater slack is no drive, taught is drive.
bananaman