Harold Willis is a name missing from the roster of British engineers who made great contributions to Motorcycling as well as their respective employers. His father purchased a large stock of shares in Veloce Ltd, perhaps to ensure his idiosyncratic and motorcycle-mad son had a job! Willis soon became indispensible to Veloce, developing and racing their motorcycles through the late 1920s and 30s. The photo below has Willis on the left, with Freddie Hicks and J.A. Baker, at Montlhery in 1928, setting the one hour/100mph world speed record on an early cammy Velo - Freddie Hick's Brooklands racer with an extra-large petrol tank.
Perhaps he's best known for his 'Willisisms', an endless stream of bon mots which succintly named just about anything of interest. A piston was always a 'bung', an exhaust pipe the 'long hole', an overhead camshaft engine was a 'knocker', a double overhead camshaft engine a 'double knocker', a valve was a 'nail', etc. He also invented the positive-stop footshifter, something we all take for granted nowadays, but a huge improvement in racing times in the day.
He also named a few of the racing motorcycles which Veloce fielded, including this one, 'Whiffling Clara', an experimental supercharged 348cc ohc single which Willis rode in the 1932 Isle of Man Junior TT. When 'Clara's' blown engine was shut off, air pressure leaked out of its plenum chamber with a sigh...hence the 'whiffling'.