The Jaguar Mark 10, or Mark X in Roman numerals, was such an odd sight that I honestly had no idea what it was until just researching it now. Not only have I not seen one, I have never even read about one.

In photos, it might be easy to mistake the Mark 10 car for a 1950s Jaguar saloon car.

But not in real life.

This Jag is quite enormous – with the upright and tall bodywork of Rolls-Royce and Bentley fame.

This (estimated) 1965 car is huge and outrageous in person. It looks like a meld of the Citroen DS and the Rolls-Royce Silver Cloud. The design really is a bit ghastly, but in a somewhat desirable way.

Note: This float-boat Jag cruiser was still petite versus American cars of the era, but makes the E-Type Coupe behind it look like a 1:2 scale model.

The Mark Ten was a gigantic limousine built from 1960 to 1970, with a cosmetic update for the 1966 model year that also changed its name to the 420G.

The D-Pillar is a mess and perhaps explains the current travesty that is the XJL’s hunchback tail and regrettable rear window mish-mash.

2014 JAGUAR XJL 3.0 AWD

I kept looking underneath for an old Pontiac Tempest frame – perhaps this monster Jag was some DIY effort or a body swap?

But this body is pure and original, as is the glass.

The wheels from the 1990s XK8 did not help identify this high-riding, flat-black Jag as original.

Only once I saw the cabin did I realize: this must be a production model!

Few body-swappers will follow through with the painstaking woodwork employed inside this Jaguar flagship of its day.

Is it beautful? No, it is not. Far from it, in fact, with a gangly rear glasshouse that shows the true purpose of this large machine: shuttling VIPs.

The Mark 10 and later the 420G made quite the names for themselves as hearses over the years, with enough room for even a VIP stiff when converted into a wagon.

The sales of this car fell rapidly when the lower and leaner XJ6 was launched in 1966, and to find a daily-driven LHD model in the Road Atlanta pit lane was quite special.

Parked with an immaculate E-Type Coupe? Even more special.

But most of all, the direct influence on today’s 2014 XJL 3.0 AWD is now as clear as day. It makes sense, but does still seem to be inspired by a pretty Fat Cat…

2014 Jaguar XJL 3.0 AWD

~1965 JAGUAR Mark 10