Just as it had done 21 years previously with the revolutionary Traction Avant, Citroën stunned the world again at the 1955 Paris Salon with the launch of the futuristically styled DS.

Beneath the shark-like newcomer's aerodynamically efficient, low-drag bodyshell, there was an all-independent, self-levelling, hydro-pneumatic suspension, plus power-operated brakes, clutch and steering.

No European car would match the ride quality of the DS for several years, and the fundamental soundness of Citroën's hydro-pneumatic suspension was demonstrated by its survival in various models for more than four decades.

In 1957, conscious that the DS was much more expensive than the car it had replaced, an entry-level model called the ID 19 was introduced.

It had the same body and suspension as the DS but was less luxuriously appointed and used a conventional braking and steering system, with a traditional clutch and manual transmission.

These changes not only allowed the ID to be cheaper than the...