A better-looking successor using 3.2- or 4-litre twin-cam ‘sixes’, voted ‘most beautiful car in the world’ by a panel of Italian style gurus. The XJR was the first to use Eaton’s M90 supercharger, meaning 0-60mph in 5.5 secs. For the 1997 XJ8 (X308), V8s replaced ‘sixes’ and V12s. The XJR 4-litre was then the most powerful Jaguar roadcar engine, boasting a supercharged 370bhp – with a rare Daimler variant called the Super V8. In Series III Double-Six Daimler form it is still the most silky car imaginable to drive. From the outside, the engine makes itself apparent more by the whirring of fans and drivebelts than any true mechanical sound. From within the cocoon-like cabin, cooled by deliciously efficient air-conditioning, the V12 feels more like an electric motor than a reciprocating unit.

Short- and longwheelbase SIIs were offered alongside each other until the LWB was standardised late in 1974, just before the introduction of the XJ 3.4 poverty model (to replace the 2.8) and Lucas injection on the V12 to curb its monstrous thirst. Injection for the 4.2 (the 3.4 stayed on SUs), and a limited range of solid colours on early cars from the troubled new Castle Bromwich body plant. Later improvements meant that with the final update for ‘sixes’ in 1985, Jaguar came fifth in that year’s JD Power customer satisfaction survey with the standard XJ6 (tweed trim) and Sovereign (leather trim) that bowed out in April 1987. Rare five-speed manual from the Rover SD1 later replaced four-speed, but most XK ‘sixes’ have Borg-Warner auto; the GM400 was later mandatory with the V12, which became the HE in 1981, boosting economy to 20mpg. Heynes’ original idea for the XJ project in the early ’60s was to create a four-door, four-seat E-type, a low-slung sports saloon that would take the fight to the Europeans in the ’70s and recapture the interest of an American market that still loved its XKEs but never quite took the MkX or S-type to its heart in the same way. Sadly, the coupé was a project that kept getting put to one side, not helped by the fact that pillarless side windows proved hard to seal against wind noise. That was why the first XJCs didn’t reach customers until 1975, by which time the arrival of the XJ-S had made it somewhat redundant.XJ40’ was the internal code for the Series III replacement. It was better built, easier to service and cheaper to run. Later cars are the best, but aren’t immune to rust. They were all AJ6 ‘sixes’ at first – including the single-cam 2.9 – with the 6-litre V12 offered for the final year. Today, interest is quietly growing in these cars. Development of the flathead, single-overhead-cam-per-bank V12 was languishing in the midst of punishing new safety requirements that were taking up too much of the tiny Browns Lane development team’s time and attention.

In fact, XJCs were only offered for two years and, while it was widely touted as a surefire future classic (almost from the day production ended), it is only recently that the coupés have begun to be appreciated for their rarity. Just 9119 were built (fewer than 1000 of those being V12s) and they came, naturally, as Jaguars or Daimlers, this one being the latter. Like every Jaguar four-door before it, the 1968 XJ6 was fast and refined beyond its price-tag, yet offered a modern interpretation of saloon-car elegance that would have floored the opposition even if the engineering underneath had not been so accomplished. The 2.8, later infamous for burning holes in its pistons, was sweeter and freer-revving, but gave away a lot of urge to the burly 4.2. Since few wealthy European buyers cared about the extra tax on an already-expensive car, or the fact it got two or three extra miles per gallon, they tended to buy the 4.2 anyway. In a funny way, these cars seem almost better now, at 50, than they did 20 years ago (when we first considered them truly ‘classic’), possessed of a lithe and compact curvaceousness that is in startling contrast to the obesity of 21st-century luxury saloons. You still have to swap between the 11-gallon pannier tanks in the rear wings, using a switch on the dashboard, but the HE (High Efficiency) V12s, featuring Michael May’s swirl-action combustion chambers, made 20mpg a realistic possibility for the first time.This laid to rest the XJ40 geneology with an allnew aluminium monocoque, bonded rather than welded for huge weight savings and gains in strength. There were petrol V6s and V8s, plus a diesel V6. The supercharged V8s give the most thrills, but complex technology and electronics don’t auger well for today’s enthusiast owners. The 2007-on facelifted X358 attempted to answer critics of the car’s ‘golf-club’ styling. The XJ was, in fact, a long-overdue fillip to the Jaguar range when Lyons personally launched it in September 1968. The optimism and certainties of the 1950s and early ’60s were fading. The existing saloons were looking old, sales were tailing off (the MkX/420G was proving a particular disappointment) and it was no longer true to say that Jaguar could sell every car it built.

Introduced in March ’79, the Series III cars were an unintended holding operation while the XJ40 was being developed. No doubt missing the input of Lyons (he retired in 1972), Jaguar turned to Pininfarina for styling tweaks that included a taller, more crisp roof and glass area, injection-moulded bumpers and flush-fitting doorhandles. Through the 1970s and ’80s the XJ became such a routine sight on British roads that we tended to forget how superlatively good they were – and still are. They are truly great machines, even when you remove your rose-tinted spectacles and waft away the fog of nostalgia that tends to surround anything with a Jaguar badge on it. The XK straight-six, at 20 years old, was still a magnificent engine and drew almost nothing but praise for its smoothness and torque. But Lyons was not satisfied. Keen to unleash his V12 secret weapon, it was with some reluctance that he had agreed to launch the car in six-cylinder form only, with the short-stroke 2.8 offered as a supplementary variant mainly for European markets, where engines over that swept volume were heavily taxed. You slide down to assume a driving position that is close to perfect, the superb vision and the sense of isolation relaxing you immediately; it feels like coming home. The end for the Series III V12s finally came in 1992, five years after the last of the ‘sixes’. Those were too heavy and too expensive to build compared to new XJ40s, which were nimbler and supposedly better-quality vehicles. Reluctant as many were to point it out at the time, though, these were nothing like as pretty as their predecessors – even if they were traditionally Jaguar in layout and feel.The Series II dash architecture largely remained – hardly the latest in ergonomics, but ‘traditional’. A variety of brittle plastic details are less welcome, the trip computer on this late Double-Six being particularly grating, but this is understandable when you consider the value for money the cars represented. Revisit any of the three XJ series today and you will be surprised by how genuinely low-slung they are, particularly in a motoring environment where everyone wants to sit sky-high in their SUVs.

The long-wheelbase 4.2 was far and away the most popular, at 57,804 cars out of a total of 127,000 SIIs (all engines and bodies). Short- and long-wheelbase versions at first, after which the SWB was reserved for the XJC coupés with 4in-longer doors. All four-door V12s were LWB, but still on carbs until the 285bhp/147mph injected 1975 car, badged XJ 5.3. ‘Blazer button’ steel wheels with hubcaps or GKN alloys on SII. Greatest oddity of the SII was the 170 exportonly 2.8s, but the 1975 3.4, with cloth seats and other luxury items deleted, is much preferred. It also represented an advance in detail refinements now that Jaguar, for the first time, took complaints about its slithery armchair seats, feeble heating and ventilation systems seriously.