[8] The name was changed to Vincent Engineers (Stevenage) Ltd. in 1952 after financial losses were experienced when releasing capital to produce a Vincent-engined prototype Indian (Vindian) for the US market during 1949.

HRD was founded by the British Royal Flying Corps (RFC) pilot, Howard Raymond Davies, who was shot down and captured by the Germans in 1917.

The company was initially bought by Ernest Humphries of OK-Supreme Motors for the factory space, and the HRD name, jigs, tools, patterns, and remaining components were subsequently offered for sale again.

With the backing of his family wealth from cattle ranching in Argentina, Vincent acquired the trademark, goodwill and remaining components of HRD from Humphries for £450 in 1928.

Massey from the original HRD company after initially working on metallurgy for Velocette,[11][12] leaving to return to his native Australia in 1949.

Vincent already looked to the United States for sales, and in 1944 Eugene Aucott opened the first USA dealership in the city of Philadelphia.

Whilst working in his office at Stevenage in 1936, Phil Irving noticed that two drawings of the Vincent HRD engine lay on top of each other in a "V" formation.

He set them out on the drawing board as a v-twin engine in a frame Vincents had made for a record attempt by Eric Fernihough, who no longer required it.

Its frame was of brazed lug construction, based on the Comet design but extended to accommodate the longer V twin engine.

[15] With 6.8:1 compression ratio, the 998 cc Series A Rapide Vincent produced 45 hp (34 kW), and was capable of 110 mph (180 km/h).

From today's perspective, it seems incongruous that Vincent could see the need for, and design, a cantilever rear suspension, as well as incorporate so many other new ideas, yet use Brampton girder forks with friction dampers up front.

[21] By 1950, the Series C had a 998 cc, 50° V-twin that put out 45 to 55 hp (34 to 41 kW), depending on the state of tune, either Rapide or Black Shadow.

[29][better source needed] During the Korean War nickel chrome steel was officially regulated, meaning the correct materials for some components (e.g. gears) were not available.

[9][better source needed][31] The Series D was a natural progression of upgraded machine specification with a modifications to the rear subframe, suspension, seat arrangement and with a new hand-operated stand.

[32] Sales declined further after the post-war motorcycling boom owing to the availability of cheaper motor cars, a little over 500 "Series D" models were made in total.

The Firefly was a 45 cc "clip on" engined bicycle built from 1953 to 1955 under licence from Miller, who were suppliers of electrical components to Vincent.

To keep development and production costs low, it used a parts-bin approach, including pieces from Vincent motorcycles, as well as wheels which came from a Morris Minor.

In an attempt to diversify the company, Phil Vincent undertook development of a version of the motorcycle V-twin for aircraft applications.

[30] Development of this engine, named Picador, began in 1951 and continued until 1954, diverting funds from the motorcycle product line.

The engine displacement was 998 cc (60.9 cu in), and it weighed 200 lb (91 kg),[citation needed] with a power output of 65 hp (48 kW) @ 5000 rpm.

The Picador motor was upgraded with a larger principal driveshaft, different big-ends, Scintilla magneto, and a double speed oil pump.

Due to ML Aviation's inability to deliver a working radio control system, Vincent did not win the contract.

Owners Club in the summer of 1955, Phil Vincent announced that the company could no longer continue in the face of heavy losses and that production of motorcycles would cease almost immediately.

[43] Whereas most were one-off builds, an early attempt at production was announced by Staffordshire engineer Tom Somerton in late 1959, with an intended low-volume run from 1960.

[clarification needed] Egli-Vincents were subsequently built under licence in France by Patrick Godet[47] and Slater Brothers in the UK.

In 1996, a new motorcycle company was formed by three individuals, Rodney Brown (a metallurgical engineer), Terry Prince (a Vincent enthusiast and specialist) and Ron Slender.

[49] Brown provided the financial start and along with Prince were the founding directors, with Slender specialising with business development post-production.

These were to be fitted, as standard, with state of the art Bosch electric start, Brembo brakes, adjustable Paioli upside down forks, Ohlins rear monoshock and V-2 multiplate clutch.

[54][55] Apart from the basic elements of the design, the Irving-Vincent was fully updated, with modern metallurgy, casting and milling allowing far stronger engine construction.

[56] The marque gained worldwide recognition by winning the Daytona (Florida, US) 'Battle of the Twins' in its first attempt in 2008, ridden by Craig McMartin.