BSA's rugged, workaday B31 was manufactured from 1945 to the end of 1959, its overhead-valve engine providing the basis for the renowned Gold Star sports roadster. At the time of its introduction, the B31 was BSA's sole all-new model, joining the lightweight 'C' and heavyweight 'M' ranges carried over from pre-war days. Produced initially with rigid frame and telescopic front fork, the B31 gained (optional) plunger rear suspension in 1949 and an all-new swinging-arm frame in '54. A good all-round performer by the standards of its time, the B31 had a top speed in excess of 70mph and could cruise comfortably all day at 60mph while returning 75-plus miles per gallon, virtues that endeared it to private owners and police forces alike. First registered on 25th March 1954, this plunger suspended B31 comes with its original old-style logbook recording only two owners (both in the Chichester area) and continuous licensing into 1966. The attached tax disc expired in May of that same year. Apparently original and complete, the machine has suffered some superficial fire damage and is offered for restoration, which should be relatively straightforward.