Here we have John Vivian Prestwich, heir to the famous J.A.P.(John Alfred Prestwich) engine manufacturing company, looking natty on a 250cc Diamond motorcycle.  Motive power is supplied by his family product, a side-valve J.A.P. engine with a total loss oiling system.  The photograph below was taken Nov 23, 1920, and his little machine recorded 62.39mph at the Brooklands speed bowl, an impressive figure for a little flathead engine of the day, and a new speed  record for the 250cc class. If you click on the photo, you might make out the lovely cursive ‘Diamond’ script on the tank.  The little bike is pared down to the absolute minimum, with the countershaft sprocket and engine plates drilled within an inch of their life, no fenders, and handlebars dropped almost to the top of the motor.  Note the finned ‘fir cone’ valve caps on the motor.  The visible levers on the handlebar are for a decompressor and ignition timing advance, and the other ‘bar would be the throttle lever.  No other controls are present or required, as there are no gears or brakes on this special record-breaker.  Prestwich’s feat would have earned them bragging rights in advertisements for J.A.P. and Diamond, as well as the oil and fuel and tires and chains they used, as was typical of the sponsorship games then as now.  Nothing so crude as stickering up this lovely racer with logos, although Vivian is not above wearing the company logo!

J. Vivian Prestwich cutting a dash aboard a lightweight Diamond motorcycle with a J.A.P. motor in 1920. [‘The Vintage Years at Brooklands’]
J. Vivian Prestwich wears a typical collegiate ‘Oxford’ sweater with the family firm’s logo and decorative bands knitted in, striped silk tie with a tie bar on his white shirt, jodhpurs, and white buck shoes.  His right shoe is a little soiled (oiled!), and he’s wearing a wristwatch, which was rare for racers at the time.  His mustache is chic but would become very unpopular twenty years later. Safety gear for racing had yet to become standardized, and helmets, gloves, leather riding gear, and boots were not universally adopted until later in the 1920’s.  Racing in the ‘Teens and early ’20s was typically a wealthy person’s sport, whether on two or four wheels, and posh universities like Oxford and Cambridge had their own motorcycle racing teams.  Young Prestwich was a dashing heir the family fortune, advertising their wares in a manner absolutely acceptable for a young man of note at that time.  Even the Prince of Wales, a motorcyclist himself, sponsored racing motorcycles at Brooklands!

H.M. Walters with his Jappic monoposto cyclecar racer, using a 350cc J.A.P. motor, with Vivian Prestwich standing behind him, in 1925. J.V.P. appears older and wiser in this photo, having taken up a role in the family business, and the associated responsibilities. [The Vintagent Archive]
Just a few years later, we see Vivian Prestwich taking up a different role in the family business, working with racing riders/drivers who used J.A.P. engines.  One notable vehicle is the Jappic cyclecar, built by H.M. Walters as a complete and integrated light racing vehicle, not merely a lashup of convenience.  The steering camber was adjustable, although it used leaf spring suspension up front (but still had modern hollow axles), and the engine was a 350cc OHV racing J.A.P. single-cylinder.  Walters and others (including Kaye Don, Gwenda Steward, and Douglas Hawkes) took many class records with this monoposto racer, starting with Walters’ 70.33mph mile record at Brooklands in 1925.  Kaye Don took a 10-mile record at 65mph in 1926, and Gwenda Stewart, using a 495cc J.A.P. motor, bumped the record to 74.48mph at the Montlhéry speed bowl in 1927.

The production version of Prestwich’s racer: the 1922 Diamon Model H Super Sports with 250cc JAP sidevalve motor. [The Vintagent Archive]

The Diamond Story

Diamond motorcycles emerged from bicycle manufacturer D.H.&S., based in Sedgley Street, Wolverhampton, England, who produced Diamond Cycles.  They were named for the now-ubiquitous ‘diamond’ frame design patented by James Starley in 1885 as the Safety bicycle, with its equal-sized wheels.  Diamond Cycles were high-quality bicycles, and sold well.  Beginning in 1908 the company added Diamond motorcycles to their sales list, using Belgian F.N. singles and v-twin engines, and the company was reorganized with new investors as D.F.&M. (Dorset, Ford & Mee) Engineering Co Ltd.  The J.A.P. connection began in 1912 with a 2 3/4hp model (250cc) using a sidevalve motor and two-speed gearbox.   Production paused between 1916-1920, and Vivian Prestwich’s ride was something of a reintroduction of the Diamond marque to the marketplace: a splash of much-needed publicity.  Diamond supported racing at Brooklands and at the Isle of Man TT through 1933, when the company ceased motorcycle production.

Things to come! The 1936 ‘pedestrian electric ‘(pedelec?) delivery vehicle. [The Vintagent Archive]
In an interesting turn, the owners pivoted to producing sidecars, both for passengers and commercial ‘floats’, purchasing the Graisley brand from A.J.S. when it went into liquidation at this time (and became part of Associated Motor Cycles – A.M.C. – along with Matchless).  The Graisley business went well, but their biggest success was producing electric utility vehicles, especially a clever electric hand truck that was popular for daily milk delivery rounds.  The Graisley ‘Pedestrian Controlled’ EV was produced all the way through 1960…60 years before such vehicles would reappear as popular ‘last mile’ delivery vehicles in urban areas.

The Graisley electric milk float, produced for nearly 30 years. [The Vintagent Archive]


Paul d’Orléans is the founder of He is an author, photographer, filmmaker, museum curator, event organizer, and public speaker. Check out his Author Page, Instagram, and Facebook.