Where does this "official distance of 72" come from?
Bob Graham Round website states:
I have read that the distance could be as low as 61 miles.The Bob Graham Round of 42 peaks is one of the most demanding challenges in England.With a ascent of app' 28,500ft and a app' distance of 74 miles.
However the distance is not important as the challenge is to reach all 42 peaks from the start to the finish within 24 hours.