The engine for these machines was derived from the unit used in the Norton Commando, which was a development of the 1948 Bert Hopwood designed 500 cc Dominator.

[8][11] Compared to other makes, the Norton engine was down on power so Williams' design tried to offset this by reducing frontal area and improving roadholding.

[4][13] More recently, Dunstall had used pannier tanks on their 1969 750 Norton racers, setting a lap record at Crystal Palace on Easter Monday and winning the 1,000 cc race at Thruxton in April in the hands of Percy Tait.

Two bikes were ready for Daytona, one for Williams and the other for Read,[11] finished in the blue and white colours of John Player.

[11] Whilst the team were at Daytona, the race shop completed a third bike for Tony Rutter ahead of the Easter Transatlantic Trophy.

[11] Read was the British captain at the Transatlantic Trophy, scoring a third place at one of the Brands Hatch races, and Williams finished third in the other.

[18] Three of the models went to Spain when they were disposed of by the factory and raced in Spanish F750 under the PDN banner, sponsored by the vintners Pedro Domecq.

[5] The double-skin monocoque was fabricated from 600 individual pieces of 22 gauge stainless steel hand welded together and weighed 37 lb (17 kg).

It contained the fuel and oil tanks and was shaped to duct cooling air to the engine and also to provide a ram-air effect airbox for the carburettors.

[3][5] A Peel-type fairing incorporating handlebar blisters and seat tailpiece were developed in the MIRA wind tunnel and the drag coefficient was reduced to 0.39.

Larger 33 mm Amal Concentric carburettors were fitted and the engine produced 76 bhp (57 kW) at 7,200 rpm.

[22] Primary drive sprockets were changed to make the gearbox run 25% faster thereby reducing the torque on the gear teeth.

The bike was returned to America after the Trophy races and stored by the Norton importers until 1977 when it passed into private hands.

The prototype in the National Motorcycle Museum (UK) and one of the racers now owned by Mike Braid, were used to obtain the correct dimensions and specification.

[2] The 1974 model was built with a compact space frame to keep the frontal area as small as possible and was again fitted with an all-enveloping peel-style fairing.

[28] The front brake was improved with Lockheed two-piston callipers acting on twin 10.5 in Norvil cast iron discs.

[28] At the John Player meeting at Silverstone in August, Williams tried a prototype frame with monoshock rear suspension.

[32] Later in August at Oulton Park, Williams had a major accident when the combined seat and tank unit became detached from the bike.

[22] The bike that Williams won on at Spa was passed on to the Benelux Norton importer, Podevyn, and was used in local F750 races.

Using one of the space frame bikes, Benjamin Grau, under the PDN banner, won all four rounds of the 1975 Spanish F750 Championship.

[34][35][36] Two JPS Nortons were displayed at the British National Motorcycle Museum in Birmingham, a 1972 pannier tank and a 1973 monocoque.

[37] To capitalise on its racing successes, Norton started designing a variant of the Commando styled to look like the John Player racers.