Italy's oldest surviving motorcycle manufacturer, Benelli was founded in Pesaro in 1911 by the six Benelli brothers, starting out as a general engineering firm repairing cars and motorcycles before turning to the manufacture of automotive and aircraft components in WWI. The firm diversified into the field of powered transport immediately after WWI, offering a two-stroke 'clip-on' power unit for attachment to a bicycle, and it was this 98cc engine, installed in a purpose-built set of cycle parts, that was used for the first proper Benelli motorcycle of 1921.
A couple of years later Benelli had a 125cc model in the range, and it was one of these, bored out to 147cc for the 175cc class, on which youngest brother Antonio ('Tonino') Benelli made his racing debut. By 1927 Tonino was racing a 172cc Benelli equipped with single-overhead-cam engine, winning almost as he pleased to take that year's Italian Championship. The sohc 175 was superseded by a short-stroke twin-cam version from which was developed the first racing 250 of 1935. By this time Benellis were winning classic races outside their native Italy, but an accident to Tonino, which caused his retirement from racing, set back the factory's competition program for the next couple of years.
Benelli was back in force for 1937 and the new 250 duly demonstrated its potential when Martelli won that year's Milan-Taranto long-distance classic. Two years later came the marque's most famous victory, when lone Benelli rider Ted Mellors won the 1939 Isle of Man Lightweight TT.
Its factory destroyed by the Allies and then looted by the Germans, Benelli took time to re-establish itself after the war. Fortunately, the racing machines had been hidden away and survived intact, providing the Italian concern with a valuable springboard from which to renew its Grand Prix campaign. Rivals Moto Guzzi secured the first post-war 250cc World Championship in 1949, but Benelli struck back the following year when Dario Ambrosini became champion at the end of a season that included wins in Switzerland, Italy and the Isle of Man. Sadly, Ambrosini's death in 1951 effectively put an end to Benelli's international efforts and it would be 1959 before the firm returned to the Grand Prix scene.
For the 1959 season Benelli developed a new, short-stroke (70x64.8mm) 250 engine that produced 33-35bhp at 10,200rpm. Despite the increase in power over its predecessor, the new Benelli 250 faced much stiffer opposition than before; by 1960 MV and Ducati were fielding twin-cylinder machines in the 250cc class and Honda had just stepped in with a four, leading Benelli to the conclusion that a multi-cylinder design was the only realistic option. Nevertheless, the 250 single did achieve one major success when Geoff Duke rode to victory in the 1959 Swiss GP, one of his last wins before retiring. Other riders who rode the works Benelli singles at this time included Dickie Dale, Silvio Grassetti and Jack Murgatroyd.
The new Benelli four's arrival having rendered the single obsolete, two were sold at the end of 1961 to British sponsor/entrant Fron Purslow, whose rider John Hartle contested several events until sidelined by injury. Mike Hailwood took over the ride, scoring a debut win on one of the Purslow Benellis at Mallory Park in May 1962, and was lying fourth in that year's Lightweight TT in the Isle of Man when the engine blew on the final lap. Percy Tait, Allen Dugdale and Ralph Bryans all rode Purslow's Benellis, but the writing was on the wall for the aging singles and their retirement lay just around the corner.