Sunday, December 10, 2006


John 'Vivian' Prestwich, the son of John Alfred Prestwich (founder of JAP motors), is here astride a 250cc Diamond powered by his family product, a side-valve JAP engine. The photograph was taken at Brooklands on Nov 23, 1920, and his little machine made 62.39mph, an impressive figure for a baby sidevalve engine, and a new 250cc record.
From the books, 'The JAP Story; 1895-1951', published in-house a year before the founder's death in 1952.  I'm still looking for details of Vivian's later life (and death - WW2?) - if you have any leads, they're welcome...
In the top photo, click to enlarge and note the lovely cursive 'Diamond' script on the tank, and how all parts are drilled to Swiss cheese standards - it much have weighed very little, perhaps only 140lbs, with I would estimate 8 or 9hp - good enough for a record on that day.  I see no linkage for a gearbox, so lurking behind that lovely drilled out countershaft sprocket is simply a shaft and bearings, much like a speedway racer - it's a single-speed, clutchless, direct-drive, all-chain racer, with a CAV magneto and Binks carb.  There are two handlebar levers - one for the magneto advance/retard, the other connected to the engine oiler, to give it a squirt now and then, direct to the big end, from whence the oil would splash around and (hopefully) oil the top end too!  It almost certainly used a cast-iron piston, which is nearly self-lubricating.
The JAP design/testing/racing department, c.1922: Vivian Prestwich, EB Ware, JA Prestwich, Stanley Greening, and Arthur Prestwich
Notes on the dashing young man, son of the scion of racing engines, who looks every bit the part. His fantastic JAP sweater is hand-knit with the family firm's logo and decorative bands, a la collegiate sweaters of the Roaring '20s.  Beneath the sweater lurks a button-down white shirt with a broad, striped silk tie, beneath which he wears horse riding breeches and WHITE buck shoes! His right shoe is soiled (oiled!), and he's wearing a wristwatch, which was rare for racers at the time.  While his moustache would become very unpopular twenty years later, Vivian's bright blue eyes shine across nearly a century, a brave, dashing young man of privilege; a real dream-boat.

Safety gear for racing had yet to become standardized or even universally worn; it took a few well-publicized, horrific racing accidents to emphasize the need for leather, and helmets, and boots, and gloves(!), all of which would become mandatory for racing in just a few years.  For the top photo, though, there's a lovely purity of a man 'at the edge', a highly romantic moment in history.


Sideburn Magazine said...

I like the look of Vivian, but Arthur looks shifty. G

Steve Brown said...

I have just republished 'The JAP Story 1895-1951'