In 1951 Jaguar relocated to Daimler's Browns Lane plant which provided not merely sufficient production capacity for their existing range, but enabled them to move into the middle-weight executive saloon sector,[7] then occupied in the UK by cars such as the stately Humbers, the bulbous Standard Vanguard and the heavy Rover P4.

The independent front suspension featured double wishbones, coil springs, telescopic dampers, and an anti-roll bar, all carried in a separate subframe mounted to the body by rubber bushes (with only minor revisions, this system was used on subsequent Jaguar saloons including early versions of the XJ).

Transverse location was secured by a Panhard rod, the system being a significant improvement over other contemporary Jaguar saloons and sports cars (the reason for the unusual inverted leaf spring arrangement was the same as for the D-Type: to transfer all rear axle loads forward to the unitary body shell.

Nevertheless, it is probable that the narrower rear track was occasioned by the lack of a suitably dimensioned component from Salisbury, the axle manufacturer.

The interior was of similar design to the contemporary Jaguar saloons and sports cars, with most of the dials and switches being located on the central dashboard between the driver and passenger.

The car was available in standard or special equipment versions with the former lacking a tachometer, heater (available as an option), windscreen washers, fog lights and cigarette lighter.

The Mark 1 was initially offered with a 2.4 litre short-stroke version of the XK120's twin-cam six-cylinder engine, first rated at 112bhp net by the factory at the launch in 1955.

The 3.4 had a larger front grille for better cooling, a stronger rear axle and rear-wheel covers (spats) were cut away to accommodate the wire wheels' knock-off hubcaps.

On 22 January 1959 former motor racing world champion Mike Hawthorn died in an accident involving his own highly tuned 1957 3.4 Litre, registration VDU 881, on the A3 Guildford By-Pass in Surrey, England.