Certain names elicit from motorcycle enthusiasts a feeling of profound reverence, names such as Brough Superior, Vincent and, of course, Bonneville. The Triumph Bonneville was released in 1959, taking its name from the achievements of Texan Triumph racer Johnny Allen on the Bonneville Salt Flats. 

The original T120 model benefitted from a big, thumping 650cc twin which assisted it quickly towards the ton, thereby making it an instant favourite with Ton-Up Boys. It wasn’t just rebellious teenagers who tried to squeeze as much speed out of it as possible, though. The Bonneville was developed for serious competition, and was perhaps most famously ridden by Steve McQueen in the 1964 International Six Days Trial.

It may be said that the Bonneville reached maturity in 1973, when the T120 was replaced by the 750cc T140. In addition to its larger engine, the T140 boasted a number of refinements including a five-speed gearbox and, significantly, a front disc brake. It had originally been intended for export only, but received such an enthusiastic reception at 1973 motorcycle shows that it was decided that it would go on sale in the home market for £679.

A few updates followed in 1975, when the engine was modified and the gear lever was moved from right to left to comply with American regulations. At the same time, a rear disc brake was also fitted. Sadly, Triumph suffered bankruptcy in 1983 which forced the closure of its Meriden works, but this was certainly not the fault of the Bonneville. Quite the opposite, in fact – the ‘Bonnie’ was in so much demand that a license was granted to Les Harris of Racing Spares in Devon to continue building in it, and in that guise the T140 lived on until 1988.

Today, one of the most desirable Bonnevilles for a collector is the T140J Silver Jubilee model, which was produced only in 1977 to celebrate the Silver Jubilee of Queen Elizabeth II. Only 2400 were made in total – 1000 for Britain, 1000 for America and a further 400 for Commonwealth export. It sported a distinctive, patriotic colour scheme of silver with a blue panel on the fuel tank and stripes on the mudguards, all outlined in red. The primary drive, rear light housing and timing covers were chromed, and the wheel rim centres were painted and lined. British-market models are identifiable by the words ‘Limited Edition’ written underneath the Union Jack stickers, and each bike was sold with a unique certificate of ownership.

Past MoTs show that this Triumph used to reside in the Leicester area. The vendor, a keen motorcycle collector, has owned it for the past 2½ years. There is no history before 2005, but the vendor tells us, “It looks to me like it was a low-mileage original bike that was recommissioned in the early 2000s and then used sparingly over summers.”

In addition to the V5, the most important document where the Silver Jubilee is concerned is the original Certificate of Ownership, which we are pleased to say remains with this bike. There is also a collection of MoTs and invoices detailing work undertaken by Supreme Motorcycles. These go back to 2005, when the mileage was only 770. The bike is currently SORNed and does not have a valid MoT.

From what we have seen of the bike, we can only say that appears to be in the very best condition from all angles. There are no obvious paint defects, and the saddle upholstery looks in excellent condition with minimal wear and no sign of cracks or splits. Perhaps the paint is not quite perfect on the frame underneath the seat, but that will not be visible most of the time, anyway. The vendor believes the paint on the wheels is original as they show the odd mark, but they are still highly presentable.

There is a lot of brightwork on this Bonneville, and it all appears to be first-rate, with a mirror finish and no sign of clouding or pitting in any of the chrome. The light lenses appear excellent, with no cracks. The rubber gaiters which sleeve the handlebars and kick-start are usually among the first places to show signs of wear, but not on this bike. The instruments look good, too, and it even sports a clock.

Although we have not seen the bike run, the external appearance of the engine is suggestive of one that has been very well looked after. The whole unit is extremely clean and does not appear to be leaking fluids. The chromed crankcase cover is clean enough to eat your dinner on it. Likewise, the Amal carburettor is very clean and we are particularly impressed by the exhaust, which is beautifully shiny and does not show any signs of sooty carbon discoloration at the tip.

The vendor has cleaned the tank and carburettors, set the points and timing, reset the tappets and changed all the oils. He tells us that “the bike starts first kick and rides perfectly, with everything working as it should”. As you’d expect, the brakes and chain are also extremely clean and do not show signs of wear, so we anticipate that this bike will be wonderful to ride. We are sure that if you were to present it for an MoT, it would pass with ease.

With all its provenance, the appeal of any Bonneville is self-evident, but if you can afford to discriminate then the Silver Jubilee is definitely one of the ones to have. Extremely rare and exquisitely finished, it’s the sort of bike you’d want to get out for special occasions, and we think this could be a potential award-winner at motorcycle shows. As they were an instant collectors’ piece, it is not unusual for Silver Jubilees to have survived as well as this one, but this is surely one of the very best.