The Jaguar 420G debuted at the London Motor Show in October 1966, introduced as the successor to the Mk X, which had been sold between 1961 and 1966. The 420G was entirely different from the 420, which was launched at the same time. With a width of 1,930mm and a length of 5,130mm, its size remains impressive even by modern standards. The chassis adopted a steel full monocoque from the Mk X, and features such as 4-wheel independent suspension, 4-wheel disc brakes, and power steering were standard equipment, showcasing the modernity of the vehicle.

The Jaguar Mk X made its debut at the 1961 Geneva Motor Show, the same venue where the Jaguar E-Type, one of the most iconic two-seater sports cars, was also introduced. However, another new model also made its debut at the same time—the flagship saloon, the Jaguar Mark X.

Before the Mk X, Jaguar's flagship models included the Mark VII (introduced in 1950 with the renowned XK engine), and its improved variants, the Mark VIII and Mark IX. For the Mk X, Jaguar completely revamped everything. The chassis became a steel full monocoque, and the body design was updated with fender-integrated, sleek lines reminiscent of the Mark 1 and Mark 2 series, which were successfully established in smaller Jaguars. The size of the Mk X was substantial by today’s standards, measuring 5,130mm in length, 1,930mm in width, and 1,390mm in height, with a wheelbase of 3,048mm. The Mk X's width would remain the widest in Jaguar history until the launch of the XJ220.

The engine was carried over from the Mark IX, a 3.8-liter inline-six DOHC, but the suspension was significantly upgraded with independent suspension on all four wheels—a double wishbone front suspension with torsion bars and a rear I-arm and trailing link with coil springs. The vehicle also came equipped with 4-wheel disc brakes and power steering as standard features, marking a significant modernization in the chassis design.

In 1966, the Mark X had its engine displacement increased to 4.2 liters, and it was renamed the 420G. This version featured design updates, such as changes to the front grille and side moldings, as well as new safety measures like a crash pad on the dashboard.

This particular car is a 1970 model year 420G, which is the final year of production for the 420G. It was imported by Shintoyo Enterprises and has a mileage of 44,000 km. The exterior has been fully repainted in the original color, and while the wheels and steering have been replaced with aftermarket parts, the interior and engine bay maintain their original condition.