Coachbuilt cars are incredibly rare things these days.

There’s a heap of reasons for this. First, there are almost no modern cars made with a separate chassis capped with non-structural body panels. A separate, load-bearing chassis construction makes it much easier and cheaper to reshape cladding panels because they do not significantly contribute to a car’s stiffness. Which is why coachbuilding was the norm in the early part of the 20th century and was commonplace up to the 1960s.

Modifying a monocoque, stressed bodyshell is much harder but was still relatively feasible until crash regulations made such re-engineering a lot more expensive. As crash requirements and other regulations have become ever more stringent, the viability of one-off or very low-volume models with extensively modified body panels has become prohibitive.

Prohibitive certainly describes the rumoured £20 million cost of Rolls-Royce’s rather beautiful new Boat Tail, of which just three are being built. They are the creation not only of the Rolls-Royce design and engineering departments but also the three owners, who were inspired by the Rolls-Royce Sweptail and the elegant beauty of J-Class yachts. The trio, who did not know each other, met Rolls-Royce people in various parts of the world and were closely involved with the Boat Tail’s creation from start to finish.

The process was aided considerably, explains a Rolls spokesman, by the fact that “they were all people we knew, all very experienced in appointing a Rolls-Royce, and they understood the bandwidth in which we can operate. When ambitions are allowed to run free, this is what motor industry can do.”

While it would be a thrill to see one of this trio if they ever turn up at a concours – and the spokesman assures me that they will be used rather than stored in dehumidified garages, although he does not reveal the countries in which they will reside – the re-emergence of coachbuilt Rolls-Royces is of little relevance to most of us beyond the pleasure of knowing that such things exist.