I came across this piece of artwork entirely by accident, when I buying a piece of Hampson artwork. The story tells a good deal about Keith.
Apparently, the person who was selling me the artwork - whose name, unfortunately, I have lost - wrote a letter to Keith saying how much Dan Dare had improved. Keith wrote back a note of thanks - and included an artboard with it. The board was never published - but it had been intended for the first half page of the first story that Keith illustrated - Operation Earthsaver. Here it is:
There was some faint text pencilled in the boxes which hasn't reproduced in this scan.
The final published version was:
The perspective in the two drawings is very different. However, how many other artists would have taken the time to reply to a small boy - and to include artwork?