When it hit the streets in 1999, the "Cool Britannia" scene was in its heyday. Madonna was busy swapping her New York drawl for cockney slang, Tony Blair was still the sultan of spin and the British people believed every word, and films like Lock Stock and Two Smoking Barrels, about East End "wide boys" knocking each other off, were box office hits.
The S-Type fitted right in. It had the look of the classic Mark II, the car of choice for every well-respecting London gangster and getaway driver in the 1960s.
Sadly, as much as the Mark II's lifecycle mimicked the stellar career of Michael Caine, the S-Type has mirrored that of Vinnie Jones. It's never materialised as a sales threat to the Germans. Here in Ireland, figures up to the end of July show that while 1,930 E-Class were registered and 1,515 5-Series, just 63 S-Types made it onto our roads this year.
Several reasons can be blamed for this: from day-one it was up against one of the greatest BMW 5-Series of all time; it never really matched the Germans in terms of interior space and trim; and it failed to offer a diesel version, crucial for those all-important Continental and company fleet sales. Now perhaps Jaguar can break into the three-figures with the latest addition to the S-Type range - a 2.7-litre common-rail diesel engine.
From its initial conception back in the mid-1990s - when it was billed as the "BMW-eater" - and its final arrival in showrooms in 1999, there were high hopes for this mid-range executive model.
We've always had a soft spot for this curvy Jaguar, with its combination of old-world charm and traditional comfort, yet in the range-topping 4.2-litre R-version, packing more attitude than Reggie Kray.
But a diesel? Surely, that's just not "pukka". On paper it seems about as intimidating as Jamie Oliver preparing a goat's cheese risotto or Del Boy in his three-wheel van.
Thankfully, when you delve deeper into the figures and get behind the wheel, you find it's just as "kosher" as current range, and may offer the S-Type a lifeline towards mainstream success.
In terms of performance, the decision to opt for a 2.7-litre unit rather than a full-blown 3-litre will obviously hinder its ability to outrun the likes of the 530d and new Audi A6 3-litre diesel. It's significantly slower than both from a standing start, and also loses out in terms of kick-down acceleration at mid-range speeds.
Yet it's no slouch, with a 0-62mph time of eight seconds and it cruises comfortably along at motorway speeds. Crucially it also sees off the challenge from its closest counterpart, the Mercedes E270 CDI.
In fairness to Jaguar, the choice was not really theirs to make, for the engine deal is part of a larger agreement between its parent company Ford and French car giant Peugeot-Citroën PSA to jointly produce oil-burning engines for use in all their marques. Regardless, Jaguar was keen to get into the diesel market as soon as possible and this is the first engine big enough to fit the bill.
It's an impressive block, not least because of the use of some advanced metals that mean it actually weighs just 15kg more than its V6 petrol equivalent. It's also a willing revver, reaching up to 4,900 rpm before the change up. In the all-important fuel stakes, with prices rising to ridiculous levels, our S-Type diesel managed 28.7 mpg in testing.
The test car was the six-speed automatic, and a six-speed manual is also available. However, the automatic is the only worthy choice, a superbly smooth box, with every ratio matched precisely to the engines output ranges.
For overtaking manoeuvres it's best to switch it to sports mode, allowing the engine to rev closer to its redline before changing, though you do need to bury the accelerator to the floor to get an immediate kick and the engine wouldn't match either the A6 or 530d in this regard.
Yet even here, when the engine is pushed to the limit, there's never any great diesel roar from the front. And this is where Jaguar deserve the greatest commendation.
What the new diesel S-Type lacks in overall punch it makes up for in pedigree. It manages to pass the ultimate diesel trick - you can't really tell it's a diesel. Despite our best endeavours to find a chink in its armour - turning off the air conditioning and heading down the motorway - there was usually more noise as the wing mirrors cut through the wind than from the engine.
In terms of sound-proofing, staff at the firm's engineering centre in Whitley have done an excellent job, arguably even better than some of its German counterparts in the cold morning start-test. The Jaguar is exceptionally quiet inside and certainly more refined than the pattering of the Mercedes and BMW engines when starting from cold.
It has all the refinement one would expect from an English gent and it never really feels harried. Though there's a little too much body roll and the suspension has a tendency to sit down in bumps on Irish roads - we even managed to scrape the bottom on several relatively normal country roads. Yet you can forgive these failings, for its balance is admirable, with a neutral cornering attitude that tends towards gentle oversteer if pushed.
The arrival of a new engine meant the designers couldn't resist doing some mid-life tweaks to the bodywork, comprising a wider grille, a re-profiled bonnet - in aluminium, instead of steel, to improve weight distribution - and a slightly raised tail. Inside, and the car still feels a little old world, all leather and wood veneer. If we were to make a purchase, we'd seek out the touchscreen control system instead of the regular large button system, just to give us a feel of the 21st century.
The S-Type also loses out to the Germans in terms of space, the rear being more a place for two than three, thanks to the large transmission tunnel running through the car, and the sloping roofline may annoy six-footers. Though the shallow boot is boosted by a 70/30 split rear seat, its 400-litre capacity is trumped by the 520 litres of the Mercedes and BMW.
In terms of pricing, the Luxury version we tested comes in at €65,865, less than most of its competitors, apart from the well-equipped Audi A6. Yet the entry-level diesel begins at €56,465, a competitive price that lets you add several extras and still within reason.
The new engine may just herald a new dawn for the S-Type and while the sun has set on "cool Britannia", this addition to the range should at least give the car a fighting chance.