I've come into this thread somewhat late too.
That early to mid 20s model of BSA sidecar hauler v-twin was somewhat popular back then,
and were often totally worn out by the time of their retirement.
They had belt rim type brakes too, not the best as traffic became heavier.
So tended to be replaced by later models with better brakes, as 1925+ had.
Not so conducive to long term survival I'm afeared ?
Nethertheless some did survive.
There are also 3 or 4 varieties of what are called the same model,
with minor changes for various markets.
Restorers take note !