It did me good loading up all the Dave Yates images through the thread, you can see from the images how the frame angles/geometry differ from the Orange Formula, Lester was a great help to be fair, he couldn't remember which one was which other than to say it was one of the first three.
But when you compare to the Overburys, its clear geometry was evolving, BB heights, chainstay lengths, headangles etc.
I found some very short racing videos, but in the space of a year you can see how things were changing so fast.