Quite what may be considered to be a prototype car is open to debate. One must remember that the V8 drive train, largely as we see it today, distinctive air filter boxes and all, was seen in lightly disguised Project Bullet prototype mules in 1973, on FWK 7**L Coventry issued registration plates. These cars are clearly identifiable as production specification TR7/8 shells, with the customary taped on fake/disguise panels, attempting to give the (then) more contemporary square look with flying buttress rear pillars, and mock square front wings in profile. Photographs survive today of these cars on test in Wales. Project Bullet was launched in 1975 as the four cylinder Triumph TR7, initially built in Speke (Liverpool). The V8 car was launched in 1977 - in limited numbers and in USA specification only - also Speke built. Bullet was designed from the word go to receive the V8 power train, i.e. what we now know as the TR7 and TR8 were developed concurrently.
It is well recorded that industrial unrest and poor quality saw production move to Canley in 1978, where incidentally the majority of the TR8s were built, and then again, for reasons best known to BL cars, to Solihull in 1980, were the final cars were built, up until the sudden cessation of production for economic reasons. Of the total of 115,000 or so wedge cars built only about 2800 were factory TR8s. The final series of cars contained a couple of 9 vehicle pre-production batches of UK spec TR8s (late 1980, early 1981), all of which were completed/dispatched in 1981. These were perhaps destined to be factory registered press demonstrators as the UK release of the TR8 was imminent. These very rare UK cars have hidden features in their VINs, and other features, that uniquely identify them. They were sold off virtually unused. We know of the whereabouts of 14 of the 18 cars, and have very complete detailed knowledge of all of them.
Back then to the factory cars used for test, experimental, evaluation, evolution, demonstration, and so on, purposes. It is interesting to do this in order of registration, but note that this does not give a definitive order of production as demonstrated earlier. I will stick generally with registrations only so as not to identify specific cars and owners too far.