Further to Cardan's comment on another thread, a brief explanation of "Ever Onward".
Barr and Stroud made precision optical equipment in Glasgow, binoculars, rangefinders etc, and this business dried up in November 1918. They cast around for something else to do, and took a license from Argyll Motors, a Glaswegian company building Glaswegian Peter Burt's single sleeve design into multi cylinder car engines. B&S wanted to break into the proprietary motorcycle engine business of JAP, Sturmey Archer, Blackburne et al. Their success was decidedly limited.
Ever Onward's engine was despatched complete with carb and magneto. The original intention is unknown, and was certainly never realised, because the engine was still basically new when Warren obtained it in 1967.
Believing that the engine deserved to be more than a static exhibit, he built a vehicle for it. It is a Norton frame with Douglas 'guards, but there are contributions from Cov. Eagle, Enfield, Levis, BSA, and sundry others unknown. It is all early twenties and quite true in that respect. Ever Onward is the result, emerging in 1968. The "name" is a statement of fact, not a brand or slogan; it is "Ever Onward", not "the Ever Onward"
Purists are entitled to tut and disparage it as the bitzer that it certainly is. Whether it is more or less of a bitzer than was produced by any and many of the small "makers" (or subsequent restorers) could be argued at length and does not matter. To me, what matters is that one of the most technically interesting engines of the Vintage era is being seen and heard by a wide audience because the thing gets used as the various original makers intended. Unusually for a flat tanker, it has decent brakes, so can and does get ridden in suburban traffic.
Sleeve valve technology has not had a lot of development when compared with poppet valves, but can by no means be dismissed as the work of crackpots. Harry Ricardo was a great enthusiast, and to this day the most powerful spark ignition engines ever built, the Bristol Centaurus and Napier Lion aero engines, were single sleeve Burt engines. Also, to this day we're still having trouble with poppet valves, despite the many millions of engineer-hours that have been applied to them over the last century.
JFerg