Launched to much acclaim in 1968, the XJ6 refined concepts embodied by previous Jaguar saloons to create a car rivalling the best offered by Mercedes-Benz.

Although introduced with XK six-cylinder power under the bonnet, it had always been Jaguar's intention that its flagship saloon would accommodate the new all-alloy V12 engine that had debuted in the E-Type sportscar, and the resulting XJ12 duly appeared in July 1972.

With a top speed of 145mph courtesy of the 5.3-litre V12's 272bhp, the newcomer combined high performance with a level of luxury un-matched by many a less-accommodating Grand Tourer costing several times as much.

The prohibitive expense of getting its two-door bodyshell to meet United States safety regulations meant that the Coupe version never went on sale in the USA, Jaguar's biggest export market.

Consequently the model is one of the rarest of the XJ family and highly sought after today by collectors.

Nevertheless, the authoritative magazine Road & Track did man...