jefmcg
Guru
Between you and an organiser. I've done it with Paul, who ran this ride. I sent a google map link of my planned route. You put google map into walk mode, and pick enough intermediate points that the total distance is >= your chosen distance. Send that to the organiser, tell him when you are doing iti, and pay him a couple of pounds. He approves it. You and he agree on what your proof will be. GPX files or receipts from each named point.
It's pretty easy once you get the hang of it.
It's pretty easy once you get the hang of it.