were already available, but the 3 Litre was an outdated, under-powered model and the 6½ Litre's image was tarnished by poor tyre performance. Tim Birkin and the Blower Bentley Sir Henry "Tim" Birkin, described as "the greatest British driver of his day" by W. O. Bentley, was one of the Bentley Boys. He refused to adhere strictly to Bentley's assertion that increasing displacement is always preferable to forced induction. Birkin, aided by a former Bentley mechanic, decided to produce a series of five supercharged models for the competition at the 24 Hours of Le Mans; Mercedes-Benz had been using superchargers for years. Thus the 4½ litre Blower Bentley was born. The first supercharged Bentley had been a 3-litre FR5189 which had been supercharged at the Cricklewood factory in the winter of 1926/7. The Bentley Blower No.1 was officially presented in 1929 at the British International Motor Show at Olympia, London. The 55 copies were built to comply with 24 Hours of Le Mans regulations. Birkin arranged for the construction of the supercharged cars having received approval from Bentley chairman and majority shareholder Woolf Barnato and financing from wealthy horse racing enthusiast Dorothy Paget. Development and construction of the supercharged Bentleys was done in a workshop in Welwyn Garden City by Amherst Villiers, who also provided the superchargers. W.O. Bentley was hostile to forced induction and believed that "to supercharge a Bentley engine was to pervert its design and corrupt its performance." However, having lost control of the company he founded to Barnato, he could not halt Birkin's project. Specifications Although the Bentley 4½ Litre was heavy, weighing , and spacious, with a length of and a wheelbase of , it remained well-balanced and steered nimbly. The manual transmission, however, required skill, as its four gears were unsynchronised. The robustness of the 4½ Litre's lattice chassis, made of steel and reinforced with ties, was needed to support the heavy cast iron inline-four engine. The engine was "resolutely modern" for the time. The displacement was : bore and stroke. Two SU carburetters and dual ignition with Bosch magnetos were fitted. The engine produced for the touring model and for the racing model. The engine speed was limited to 4,000 rpm. A single, crossflow, overhead camshaft actuated four valves per cylinder, inclined at 30 degrees. This was a technically advanced design at a time where most cars used only two valves per cylinder