Jaguar 420 and Daimler Sovereign (1966–69)

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Jaguar 420 and Daimler Sovereign
1968 Jaguar 420 1967 Daimler Sovereign
ManufacturerJaguar Cars
Jaguar 420 - 10,236
Daimler Sovereign - 5,824
SuccessorJaguar XJ6
ClassSports saloon
Body style(s)4-door saloon
LayoutFR layout
Engine(s)4.2 L XK I6
Transmission(s)4-speed manual (Jag only); 4-speed manual/overdrive; or 3-speed automatic options available
Wheelbase2737 mm (108 in)
Length4762 mm (187 in)
Width1702 mm (67 in)
Height1429 mm (56 in)
Curb weight1676 kg (3695 lb)
RelatedJaguar Mark 2
Jaguar Mark X
Jaguar S-Type
ManualsService Manual

The Jaguar 420 (pronounced "four-twenty") and its Daimler Sovereign equivalent were produced for a short period at the end of the 1960s as the ultimate expression of a series of "compact sporting saloons" offered by Jaguar throughout that decade. They should not be confused with the larger Jaguar 420G.


The Jaguar Mark 2 was introduced in 1959 and sold through most of the 1960s. It had a live rear axle and was powered by the XK six-cylinder engine first used in the Jaguar XK120 of 1948. In the Mark 2 the engine was available in 2.4, 3.4 and 3.8 litre capacities.

In 1961 Jaguar launched two new models. The Jaguar Mark X (pronounced "mark ten") saloon used a new independent rear suspension and a triple SU carburettor version of the 3.8 litre XK engine. The other new car for 1961 was the Jaguar E-Type sports car, which shared the same engine as the Mark X and a scaled down version of the independent rear suspension. In 1965 the Mark X and E-Type were updated with a new 4.2 litre version of the XK engine, still with triple carburettors.

Meanwhile, in 1963 Jaguar had introduced the Jaguar S-Type as a development of the Mark 2. It utilised a mid-scale version of the Mark X independent rear suspension in place of the Mark 2's live rear axle. Other differences over the Mark 2 were extended rear bodywork to provide for a larger boot, a changed roofline for more headroom, a slightly plusher interior and detail differences around the nose. The S-Type was available with either 3.4 or 3.8 litre XK engines (only 3.8 litre in USA) but in twin carburettor form because the triple carburettor setup would not fit into what was essentially still the Mark 2 engine bay.

In August 1966, Jaguar added to this range two new saloons which combined the 4.2 litre powerplant of the Mark X and E-Type with the compact body and independent rear suspension of the S-Type. These were the Jaguar 420 and Daimler Sovereign, the two models being almost identical.


Jaguar 420
Jaguar 420 interior

The 420/Sovereign featured a squared-off nose with four headlamps to improve aesthetic balance compared with the S-Type and create a family resemblance to the Mark X, (which was renamed "420G" at the same time). The 4.2 litre engine was fed by just two carburettors and developed 20 bhp (15 kW; 20 PS) less than the version in the 420G and E-Type. In "Jaguar S Type and 420 – The Complete Story", James Taylor suggests that this was due to a wish by Jaguar to avoid stealing sales from the 420G.[1]

Interior changes were driven mainly by safety considerations, with the wood cappings on the doors and dashboard being replaced by padded Rexine and only a wooden garnish rail remaining on the tops of the door linings. The adoption of an electric tachometer meant that the cabin clock had to be relocated from the tachometer to the centre of the dashboard top rail, where it was powered by its own battery.

Apart from the 4.2 litre engine, other mechanical refinements the 420/Sovereign had over the S-Type included:

  • variable ratio power steering (Adwest Marles Varamatic), an option on the Jaguar but standard on the Daimler
  • replacement of the Borg Warner Type 35 automatic transmission with the stronger Model 8
  • brake discs featuring a peripheral cast-iron anti-squeal ring
  • a viscous coupled "Torquatrol" engine cooling fan
  • a larger and more efficient cross-flow radiator
  • an alternator in place of the dynamo
  • a pre-engaged starter


Jaguar 420 engine bay

Contemporary road tests[2] indicate that the performance of the 420 and Sovereign was very highly thought of.

A Motor (UK) road test in May 1967 reported:

"It seems somehow insolent to apply medium [price] standards to a saloon that for a combination of speed, comfort and safety is as good as any in the world, regardless of cost"

A North American perspective was provided by Road & Track, whose December 1967 report concluded:

"Jaguar's big seller in the U.S. remains the E-type sports cars, but the 420 sedan offers just as unique a combination of qualities in its own field. For a reasonable basic price of $5900, Jaguar offers brisk performance, outstanding braking, excellent handling and ride, quality finish, and luxury in abundance, all in an automobile that's easy to maneuver in today's maddening traffic"

A road test by Wheels (Australia) in August 1967 enthused:

"While they can continue to build and sell cars as good as this, there is hope for the man who cares about his motoring"

In terms of performance measured under test conditions, 0–60mph in under 10 seconds and a top speed of over 125 mph (201 km/h) were typical. The factory-quoted horsepower rating of 245 bhp (183 kW; 248 PS) was often referred to as being rather optimistic, with the consensus being that about 180 bhp (134 kW; 182 PS) was more realistic. Among the few exceptions the testers took was to the 15-16mpg fuel consumption, which even for the late 1960s was rather high.


Daimler Sovereign
Daimler Sovereign engine bay

There were few substantive differences between the Daimler Sovereign and Jaguar 420. Whereas the Daimler 2½ litre V8 of 1962 differed from the Jaguar Mark 2 in having a genuine Daimler engine, only the Sovereign's badging and aspects of interior trim differentiated it from the 420.

The Daimler differed from the Jaguar in having:

  • a fluted radiator grille with stylised D badge in place of the smooth crowned and Jaguar-badged grille
  • a flying D mascot at the forward edge of the bonnet in place of the 'leaping cat' Jaguar mascot above the radiator grille
  • a plastic insert on the rear number plate housing bearing the Daimler name. On the 420 a recess in the cast number plate housing bore the Jaguar name and on the Sovereign this remained beneath the plastic 'Daimler' insert
  • ribbed camshaft covers bearing the inscription ‘Daimler’ rather than ‘Jaguar’, (although earlier versions shared the same polished alloy covers)
  • wheel trim centres, horn button, oil filler cap and seat belt clasps carrying the stylised D rather than the title Jaguar, a Jaguar’s head or no badging at all
  • all of the 420 extras as standard, including overdrive on manual transmission cars and power assisted steering
  • arguably more carefully selected and matched walnut veneer trim
  • higher grade seat leather with perforated centre sections
  • better quality covers for the sun visors


The larger, Mark X-based Jaguar 420G

Difficulty in differentiating the 420 and Sovereign from other models has been a significant factor in making them less familiar to enthusiasts and the general public alike.

At the same time as the 420 was released, Jaguar added more chrome to the Mark X and made changes to the interior, renaming it 420G (with "G" for "Grand"). Given the similarity between the names and frontal styling of the 420 and 420G, the casual observer might be forgiven for mistaking one for the other.

Daimler DS420

In 1968 the Daimler DS420 limousine began to be produced, using the 4.2 litre Jaguar engine in twin carburettor form and undergoing final assembly at Jaguar's Browns Lane factory in Coventry, England. Although this car was based on a modified 420G floorpan rather than that of the 420, the existence of a third Jaguar-manufactured model with "420" in its name provided further scope for confusion.

Similar confusion arises in regard to the Daimler Sovereign. From late 1969 its Jaguar XJ6 based successor continued with the Daimler Sovereign name until 1983, when "Sovereign" was instead applied to the high-specification version of the Jaguar, (which by then was into its Series III XJ6 iteration).


Another reason why the 420 and Sovereign are less well known than other Jaguars and Daimlers is that relatively few were made. The Coventry factory stopped making the Jaguar 420 just over two years after production began and with just 10,236 produced. The Daimler Sovereign continued into 1969 but only 5,824 were sold. Nevertheless, for the time it was in production, the 420/Sovereign easily outsold any other Jaguar saloon model (i.e. the 240 and 340 Mark 2s, S-Type and 420G) and effectively ended buyer interest in the S-Type.

By the end of the 420/Sovereign production run, buyers were hanging back to wait for the new Jaguar XJ6. Introduced late in 1968, the XJ6 was slightly larger than the 420 and swept it from the Jaguar range along with the Mark 2 and S-Type. The 420G remained in production until 1970.

The Jaguar 420 ceased production at Browns Lane in September 1968 and the Daimler Sovereign in July 1969, although CKD ("completely knocked down") Jaguar 420 kits were supplied as late as November 1968 for assembly by Jaguar Cars South Africa Ltd .



Engine Jaguar 6 cylinder in line, iron block, alloy head
Capacity 4235 cc (258 CID)
Bore/Stroke 92.07 mm (3.6 in) x 106 mm (4.2 in)
Valves DOHC 2 valves per cylinder
Compression Ratio 8:1 (7:1 and 9:1 optional)
Max. Power 245 bhp (183 kW; 248 PS) @ 5500 rpm [180 bhp (134 kW; 182 PS) is thought to be more realistic]
Max. Torque 283 lb·ft (384 N·m) @ 3750 rpm
Carburettors Twin SU HD8 (2 in)
Suspension Front independent, with wishbones, coil springs with telescopic dampers and anti-roll bar

Rear independent, with lower wishbone and driveshaft as upper link, radius arms and twin coil springs with telescopic dampers

Steering Recirculating ball, worm and nut; Varamatic power assistance optional on Jaguar (standard on Daimler)
Brakes Servo assisted discs on all four wheels, inboard at rear
Body/Chassis Monocoque bodyshell with bolted front subframe, five seater saloon, front engine rear wheel drive
Tyres/Wheels 6.40 x 15 crossply or 185 x 15 radial, 5.5 in rim, five-stud disc wheels with wire spoke optional
Track Front=1410 mm (56 in) Rear=1384 mm (54 in)


  1. Taylor, James. "Jaguar S Type and 420 – The Complete Story", Crowood, ISBN 1-85223-989-1
  2. "Jaguar S Type & 420 – 'Road Test' Limited Edition", Brooklands Books ISBN 1-85520-3456

Further reading

  1. "Jaguar 420 Service Manual", Jaguar Cars Limited ISBN 1-85520-171-2
  2. Ball, Kenneth. "Jaguar S Type, 420 1963-68 Autobook", Autopress Ltd ISBN 0-85147-113-7