OP's Puzzle #1589 Julien MM 5 Prototype

[Otto Puzzell]

Know what it is?

Please, respond below and share your knowledge of what this is, and who built it.
As always, detailed answers are greatly appreciated by all. 
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Thanks!

[Otto Puzzell]

No Rookie guesses at all.

[studhamsmudger]

Julien MM5?

[Otto Puzzell]

Sounds right - I'll check the answer at home.

[Wendax]

It is not "2 CV-based" which would imply a Citroen connection. It is just an engine size classification for fiscal reasons.