The final phase of the Triumph twin's development began in 1972 with the first appearance of the new 750cc version of the Bonneville, the increase in bore size necessitating a new crankcase to accommodate the larger barrels. Other improvements included a new ten-stud cylinder head, triplex primary chain, stronger transmission and a disc front brake. A five-speed gearbox, introduced on the preceding 650 Bonneville, was standard equipment on the 750. Despite the age of the basic design and strong competition from Japanese and European manufacturers, the Bonnie remained for many years the UK's top-selling 750. In 1977 Triumph introduced a special, limited edition Bonneville to celebrate HM Queen Elizabeth II's Silver Jubilee. This was basically the standard Bonnie enhanced by a red, white and blue on silver finish, coachlined cycle parts, and a chromed timing cover and primary chaincase.

This example of one of the more collectible of later Bonnevilles was purchased new by the vendor's father, who was proprietor of a petrol station in West Kingsdown near Brands Hatch. One of his customers was Paul Smart, whose firm Paul Smart Motorcycles of Maidstone supplied the Triumph, which arrived unregistered and with a dry battery. The Certificate of Ownership is signed by both Paul Smart ('thanks for the money') and his brother-in-law, Barry Sheene ('with best wishes').

The Bonnie was stored in silicone bags, the manufacturer's protective wax remaining on it until 2-3 years ago when it was removed so that the machine could be exhibited at the National Motor Museum, Beaulieu where it was displayed for three years. Never started, the machine has only 'push miles' recorded on the odometer and is described as in superb original condition apart from a defective front brake. The original owner's handbook, leather key fob and vehicle registration application form are included in the sale together with the NMM description and the aforementioned Certificate of Ownership.