I saw this images online so thought I'd share.
The first image shows a sketch of the Mk1 and how it was fleshed out to become the Mk2 we know and love - interesting that it depicts a 5 door.
(https://eddypeck.files.wordpress.com/2020/03/mk1tomk2.jpg)
The following images are part of the clay modeling prototype stage. Note on one of the pics the rear arch is shown a lot more squared off than the final rounded arch we ended up with. I think they made the right decision.
(https://eddypeck.files.wordpress.com/2020/03/mk1tomk2-2.jpg)
(https://eddypeck.files.wordpress.com/2020/03/mk1tomk2-3.jpg)
(https://eddypeck.files.wordpress.com/2020/03/mk1tomk2-4.jpg)
(https://eddypeck.files.wordpress.com/2020/03/mk1tomk2-5.jpg)
(https://eddypeck.files.wordpress.com/2020/03/mk1tomk2-6.jpg)