BSA S31 Sloper
GK1564 is a 1931 493cc example of a BSA 'S' series, fitted here with a Graiseley Launch sidecar. The series was made between 1927 and 1935. The two digits after the 'S' in the model number indicates the year of manufacture, but why 'S' is unknown. Was it because of the sloping engine, the saddlebag tank, sporty, silent? Whatever it might have been, it was just called the 'Sloper'
They became popular with police forces forming their first traffic divisions following the introduction of the 1930 Road Traffic Act which introduced speed limits and driving licences.
Top speed 70-75 mph.