BSA M20

The First World War had popularised ‘mechanical transport’ to such an extent that the Automobile Association had to become more mobile in order to service its growing membership. The existing cycle mounted patrolmen could only cover a ‘beat’ of eight to ten miles.

At a members’ committee meeting in April 1919, the Secretary proposed spending £15,000 on setting up ‘Road Service Outfits’; motorcycles and sidecars with specially built ‘side carriers’ to provide ‘mechanical first aid’ from ‘miniature workshops’. They would be ridden by specially recruited ‘trained men from the War’ :the Army Service Mechanics. The outfits would cost £100 each to buy and prepare and running costs were estimated at £75 a year. A drawing of the now famous AA sidecar box was tabled and criticised for looking too much like a coffin! The proposal was however carried unanimously and so the AA became motorised.

The first machines were military surplus and it was not until the advent of the side valve M Series BSA of 1937 that the AA began to standardise on the M20 and M21.
The robust utility M20 was nicknamed the ‘soldier’s friend’ in the Second World War with over 100,000 being delivered to the British Army. The 500cc single cylinder engine gave 28bhp and its low stress gave it a ‘life expectancy’ of around 50,000 miles.