Designer Bert Hopwood had his hand in most of the mid-century vertical twins that changed the British motorcycle industry. He started with Val Page at Ariel in 1936, worked under Edward Turner on the 1937 500 cc Triumph Speed Twin and then went back to work for Page again in 1948 to improve the 500cc BSA A7 twin.

In 1947, Hopwood also worked for Norton on the 497 cc Dominator twin, which struggled to pull a heavy prewar frame on 6.75:1 compression ratio designed for “pool” petrol. It was smooth but slow, which was just as well as the handling was not great. The Dominator engine was a 360-degree, long-stroke twin with a single camshaft in the front of the engine. The rocker box was integral with the head, which meant one less gasket to leak.

In 1952, however, the Dominator 88 got Rex McCandless’s new “featherbed” frame, which had been developed for the racing Norton Manx in 1951. It was made by Reynolds, as Norton did not have the welding equipment. Light and strong, the featherbed revolutionized the industry and delivered excellent handling. The “Dommie” engine still only put out 29 bhp, so some enthusiasts took matters into their own hands and fitted more powerful Triumph twins to create the first Tritons.

The Norton Dominator 88 was the first production roadster to get the featherbed chassis and the model was updated through the 1950s, with alloy cylinder head and full-width hubs in 1955, then welded rear swing-arm sub-frame, alternator electrics and coil ignition. For 1956, the 600 cc Dominator 99 was introduced. The extra 100 cc meant that the magic “ton” (100 mph) was firmly in reach, and the model became a favorite of Rockers, who fitted clip-on bars, alloy tanks, cutaway fenders and megaphone exhausts.

The narrow “slimline” frame was fitted in 1960, with the top rails closer together; two-tone paint schemes were introduced, and a large metal tank badge added. The 650cc Manxman was built in 1960 and 1961 for the U.S. market. It had high cruiser bars, a bright blue tank and a red seat with white piping.

In September 1961 the 650 cc Super Sports was launched and the 600 cc Dominator 99 was discontinued, followed by the 500 cc Dommie 88 in 1963. The faster SS continued through 1966, with twin carburetors and flat bars, though alternator/coil ignition was dropped in 1962.

Norton was still wedded to the Manx single for racing and the racing Dominator, called the Domiracer, never received whole-hearted support or development. The bikes still proved quite competitive, though, and Tom Phillis managed the first 100 mph lap of the Isle of Man on a pushrod twin in 1961, finishing third in the Senior TT. When the Domiracer shop closed in 1962, ace tuner Paul Dunstall bought the spares and continued to develop the bikes, even selling a Dunstall Norton to Steve McQueen.