Irving was an Australian motorcycle designer, engineer and talented mechanic, and some months after arriving in England he signed on with Vincent-HRD. The first thing Irving did was rework Vincent's frame into something that looked much more appealing to the motorcycle-buying public (although he retained its rear suspension), and sales started picking up.

The first Vincents used JAP and Rudge engines, but quality control problems led Vincent and Irving to design their own 500cc single in 1934. This single had a unique valve train with the camshaft located high in the crankcase (sometimes referred to as a “semi-overhead cam”), shortening the pushrods of the overhead valve engine. With metallurgical  improvements making short-stroke engines practical, Vincent specified a bore and stroke of 84 x 90mm.

The two Phils next put their minds to the design of a twin. The Rapide, nicknamed the Snarling Beast or the Plumber's Nightmare — depending on whether you loved the power or hated the looks — debuted in late 1936. This 998cc V-twin was easily capable of over 100mph, incredible speed for a street motorcycle in the Thirties.

After World War II broke out, Vincent and Irving spent their time making war materiel during the day and planning for a return to motorcycle production at night. In 1946, less than a year after the end of the war, they introduced the Series B Rapide. The B’s transmission and clutch were integral with the crankcase, and the massive drive train was employed as a stressed part of the chassis. Each rocker arm acted on a collar mounted in the center of the valve, and double valve springs and twin valve guides, along with the high camshaft, increased valve accuracy. This was the start of the Vincent legend.

Vincents were soon exported to the United States, where they were snatched up by folks with a need for speed. In 1948, Rollie Free blasted the speed traps at Bonneville at more than 150mph, and trumped his own record in 1950 at more than 160mph. The Series B evolved into the Series C, with its distinctive Girdraulic combination girder and telescopic forks, and then the Series D, with innovative fiberglass enclosure. Unfortunately, the Vincent company, never very financially secure, had a run of bad luck and was forced into bankruptcy in 1955.

But the demise of the Vincent company had little effect on the enthusiasm of Vincent owners. 

In the mid-Sixties, Swiss custom builder Fritz Egli started buying up Vincent engines and began producing his Egli-Vincent. Offered as complete bikes or kits, Egli-Vincents incorporated the potent Vincent engine in an excellent frame, with an oil tank incorporated in the backbone. Although Egli discontinued building the Vincent frame years ago, copies are still being built in France, England and Australia, a testimony to the enduring quality of Egli’s frame design.