Triumph's early output was confined to sidevalve machines but in 1921 the appearance of the Coventry firm's first overhead-valve model caused a sensation. Based on the existing SD ('spring drive') model, whose frame and engine bottom end it inherited, the 3½hp (500cc) newcomer sported a four-valve cylinder head designed by automotive engineering consultant, Harry Ricardo. Although the 'Riccy' was unsuccessful at the Isle of Man TT races, a works bike ridden by Frank Halford broke the world flying mile record in 1921 with a speed of 83.91mph. The first production models arrived in 1922 equipped with a cast-iron rather than the racer's steel cylinder barrel but otherwise were much the same, featuring paired parallel valves set at 90 degrees in a pent-roof combustion chamber, bifurcated inlet port and separate exhausts. Druid girder forks were fitted until Triumph's own design was ready. Economy rather than outright performance was the road-going Riccy's strongest suit, in excess of 100 miles per gallon being within reach at moderate cruising speeds. Although Rudge went on to make a success of their four-valve designs, Triumph's did not last into the 1930s, being dropped at the end of 1927.

First registered on 28th March 1923, this 'Riccy' was found by the current vendor in a barn in 1959 carrying a 1929 tax disc, suggesting that it had been there for the preceding 30 years. We are advised that the engine and gearbox were in very good condition while the paintwork and plated parts needed extensive restoration. New wheel rims, spokes, tyres and tubes were fitted; the engine stripped and rebuilt; and all enamel paintwork shot-blasted and' aluminium sprayed before repainting. All nickel work was professionally re-plated and the saddle re-covered in leather. The Triumph had been brought back to its original condition by 1975 and subsequently entered two Banbury Runs and various local rallies and steam fairs. Since 1982 'NK 5273' has been stored in a variety of museums and garages and it would now benefit from re-commissioning (including wiring-up the electrics) to return it to roadworthy condition. The machine is offered with old-style duplicate logbook (1959), sundry restoration invoices and Swansea V5. (It should be noted that both registration documents incorrectly record the engine capacity as 350cc).