StoneRoad2013's photos with the keyword: M21

caption text for the above image reads : "With the reduction is the currency allowance for overseas travel, the emphasis will be on holidays at home. In anticipation of a record motoring season, the AA is increasing it's road patrol service. This picture shows the AA man, having just collected their new machines from the BSA factory leaving for their 'beats' in all parts of the country in time for Whitsun." Estimating that there are at least 50 outfits shown here, BSA M21 600cc {actually 591cc sidevalve engine} will be the motive power ...

Significant contrast in military motorbikes. on the left is a BSA M21 [600cc side-valve] from WW2 [development began in 1937]. The M20 & M21 were some of the most numerous models supplied to the British Army. on the right is an Armstrong MT500, developed in the 1980s. Note then lighter construction and much higher ground clearance.