1955 Vincent 998cc Black Prince

Only 844 miles from new
1955 Vincent 998cc Black Prince

Frame no. RD12508F
Engine no. F10AB/2B/10608
Crankcase mating no. E74V


  • Only 4 owners and 844 miles from new
  • One of only some 200 enclosed models produced, 104 Black Prince models
  • Matching numbers
  • Supplied by Harper Engines Ltd
  • Runs and rides ‘like new’

Ever since the Series-A’s arrival in 1937, the Vincent v-twin had been synonymous with design innovation, engineering excellence and superlative high performance. So in September 1955 when it was revealed that production of the Stevenage-built machines would cease, the news stunned the motorcycling world. It had been decided that the firm’s future lay in more profitable lines of manufacture, and just 100 more of the fabulous v-twins would be completed. By the time its demise was announced, Vincent’s final twin – the Series-D – had been in production for just six months. 

It had been Philip Vincent’s belief that provision of ample weather protection combined with enclosure of engine and gearbox, would make the Vincent Series-D the ultimate ‘gentleman’s motorcycle’ and to reflect this change of emphasis the enclosed Rapide and Black Shadow were known as Black Knight and Black Prince respectively. In actuality, delayed delivery of the glassfibre panels – plus continuing demand for traditionally styled models – resulted in over half the production leaving the Stevenage factory in un-enclosed form. 

Other Series-D innovations included a new frame and rear suspension; a steel tube replaced the original fabricated upper member/oil tank while the paired spring boxes gave way to a single hydraulic coil-spring/damper unit offering a generous seven inches of suspension travel. In place of the integral oil reservoir there was a separate tank beneath the seat. The user-friendly hand-operated centre stand was a welcome addition, and there were many improvements to the peerless v-twin engine including coil ignition for easier starting and Amal Monobloc carburettors. Sadly though, the Shadow’s magnificent 5″-diameter Smiths speedometer had been replaced by a standard 3″ unit. 

Notwithstanding the fact that, as far as Philip Vincent was concerned, the Series-D was his finest design, the motorcycle-buying public greeted the innovative new models with suspicion, as is so often the case. The appeal of the Vincent, and the Black Shadow in particular, lay in its ability to out-perform just about every other vehicle on the road, and in the early post-war years there was nothing to compare with it. This was a time when the average family saloon was barely capable of reaching 70mph, and not until the advent of Jaguar’s XK120 was there a production sports car that could live with the thundering v-twins from Stevenage. Its creator’s vision of the Series-D as a two-wheeled Grande Routière just did not conform to the public’s perception of the Vincent as the ultimate sports motorcycle. The firm lost money on every machine made, and when production ceased in December 1955 only 460 Series-D v-twins had been built, some 200 of which were enclosed models like the example offered here.

This Black Prince was imported in 1966 from Harper Engines Ltd, which had acquired the defunct Vincent Engineers (Stevenage) Ltd in 1958. Harper’s continued to produce Vincent spares and offered repairs and servicing, and sold fully refurbished machines such as this bike for a time during the 1960s. The first owner, one Matt McConnaugh used it very little before passing it on to the bike’s second owner through famed Merrimack Motorcycle Sales, or as it was more commonly known, Coburn Benson’s Vincent Farm. The bike can be seen in front of Benson’s shop in the very late 1960s in the featured photo below. This new owner, Ron Burns, who was the inventor of a key tool used in cancer research, an accurate computer-based X-ray detector for molecular analysis, which provided a huge technological leap forward and is now one of the most important tools used in cancer research. Burns was an amateur racer, primarily of 2-stroke machines in the early 1970s and purchased the Vincent, but instead of using it as it was designed, kept it as the art piece many consider it to be and having drained fluids, displayed it in his living room for many years. 

In 1989, the bike passed to the third owner, a long-time VOC member in Cambridge, Mass. With only 840 miles displayed on the odometer, it was deemed to special to be ridden and remained in a pickled state on static display. 

Finally, a couple of years ago, it passed to the fourth owner. A local Malibu-based collector or some very exotic vintage cars and motorcycles, he spotted the bike for sale with great familiarity. As a wrench-turner for Coburn Benson in the late 1960s and early 70s, he was all too acquainted with the machine, its history and provenance. Having purchased the bike, it went directly to a marque expert shop for detailing, re-commissioning and service. The bike was returned in fine running condition, before again, being prepared and placed on static display, now with what is truly believed to be a genuine 844 miles from new.

Mechanically, the bike is excellent, and we are assured that engine internals are in exquisite condition as well. The cosmetics show the patina of a 75-year-old machine, that has been meticulously cared for. The windscreen has crack from age, but a new-old-stock screen is included in the sale. 

This sale represents a unique opportunity to acquire one of only approximately 100 manufactured, so an incredibly rare, top-of-the-model-line Vincent Black Prince, with unrivalled ownership history, originality and mileage. A supremely collectible machine.

Asking $99,000


Vincent Black Prince #10608 in front of Coburn Benson’s shop, c.1969, third from right

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