Background: Jaguar's 420 was introduced in 1966 as a bridge between the Mk II and the larger Mk X, providing a more refined and luxurious option within the Jaguar saloon range.

Building on the successful S-Type platform, the 420 featured a new, more squared-off front end with a four-headlamp design, setting it apart aesthetically from its predecessors.

The 420 was powered by the 4.2-litre XK engine, also used in the Mk X and later the 420G, producing around 245hp.

This powerplant, combined with either a manual or automatic transmission, offered a compelling blend of performance and comfort.

The 420 maintained Jaguar's reputation for sporty handling, thanks to its independent rear suspension and well-tuned chassis, despite its more luxurious leanings.

While the 420 filled a niche market and provided a valuable stepping stone between the Mk II and the upcoming XJ series, it struggled to achieve significant sales success.

Its positioning as a middle-ground option did not resonate a...