Solved - MJW #309 - Jaguar Mk VIII with a 1935 Arnold body. Built by Arthur Billard 1965-1972.

[Aaron65]

Corsica?

[woodinsight]

Arnold is correct. One point to Wendax.

As I don't think anyone will know the man behind this car, I'm going to call it solved now.

Just to sum up what the puzzle car is -

It's basically a Jaguar Mk VIII that has been fitted with a modified Arnold body that was originally on a 1935 Bentley Sports Saloon. The main conversion took place 1965-1972 but improvements are still being added.
The man behind this car was Mr. Arthur Billard of Sheffield, Yorkshire.
Quite a retirement project!