J.G. Ballard wrote this

J.G. Ballad wrote a "treatment" for the film when Hammer first decided to make a non connected sequal of sorts to One Million Years, B.C.

A treatment is not a script, per se, but a "what happens" transcript that can be anywhere from a few paragraphs to many pages.

Ballard's original idea was to do a high key comedy much closer to (but not exactly like) the FLINTSTONES than to One Million Years B.C. At the last minute Hammer got cold feet and when they hired Val Guest to direct, he wrote a more familiar script...

Jim Danforth had the original treatment, the comedy, and he said to me when we worked together at Cascade, "You want to read it? I'll bring it in."

I said "no, that's ok."

I wish I had read it now. I can only assume that the original intent by Ballard was more like CAVEMAN with Ringo Starr, made ten years later.

http://www.woodywelch.com

Ballard gives an account of his involvement with this film in his memoir Miracles Of Life. He describes his meeting with the film people, and finally remarks that upon seeing the finished film, he was relieved that his name is spelled incorrectly in the credits.