Even now, years after it ceased production, the Jaguar XJ6 rates as a truly elegant-looking car, somehow defying the normal design logic of a four-door saloon. These days they’re probably a bargain buy, particularly if you can get a well-sorted one.

Here’s what David Wright had to say in our buyer guide: When Jaguar introduced the XJ6 to motoring media on 26 September, 1968, at the Royal Lancaster Hotel in London, there was effusive praise but perhaps little understanding of how Jaguar’s finest car to date would eventually speak volumes about the decline of the once-great British car industry.

At its launch, Jaguar’s engineering boss William Heynes said the XJ6 had been designed for a seven-year production run. No-one could have predicted in September 1968 that it would effectively be built for 24 years - and it would be 18 years before a successor was released!

Jaguar – as Swallow Sidecars – was founded and run by William Lyons – yes, Jaguars and Lyons – who had a great eye for design and arguably an even better one for business. Lyons drove a hard bargain with his suppliers and even before World War II, his cars offered remarkable value for money.

If there is a flaw to acknowledge in any account of the XJ6 it is that cost-cutting was reflected in the quality of many of its components, although this was artfully disguised when the cars were new.

Before the arrival of the new Jaguar, there were four different sedans: the 240/340 (successors to the Mark 2), the S-Type, the 420 and the gargantuan 420G (a 4.2-litre Mark X by a less charismatic name). The XJ pensioned off all four with a choice of 2.8 or 4.2-litre straight six engines.

Few cars of the second half of the twentieth century – let alone our 1970s decade – are as celebrated as the XJ6. While observations about worse than average reliability surfaced quite early on, these were rarely more than slight qualifications to rave reviews. Comparison tests generally proclaimed it the winner over all rivals including the previously untouchable Rolls-Royce Silver Shadow.

(See tradeuniquecars for our XJ buyer guides.)