If I remember right, the prototype BA GT/P in blue that was at the motorshow had a different hump in the bonnet. The end of the hump was shorter and steeper from the front edge and less smoother than that came out in the production vehicles. I also remember that the first posters of the GT also had the different bonnet. I recall that caused a reaction from the crowd and caused Ford to go back and change the design before production started. I am sure I have a photo of it that I'll try and dig out.
The only reason they changed the bonnet was because of the high rate of scrappage of the first version. It would split when pressed. So they were forced to change the design to prevent that from happening. Hence getting rid of that front crease which was causing the problems. As you can see the second version is much smoother and much less inclined to split the metal when pressed.