Ah, it was Jan Jackson! Here he is with his map of the possible routes!

https://www.facebook.com/jan.jackson.1848?__tn__=%2CdlC-RH-R-R&eid=ARDAkkHLvtf5jLFFzm0_KkFx6YTgwXIQXe6skew4wUL-gtpUxRvhkHpAeuy3gcPBiXNhnh_GnL7cA7m4&hc_ref=ARTfMpHESBXJ2kwvdM9W6FuGhP-Kx_zwrP8UPvyF7g-QgFhK_z4CS77xpwho-OVJBGM

As can be seen, two of his routes went over Redhorn Hill but they start at Avebury which we now know is wrong. The third, starting from West Woods went through the Vale of Pewsey and the River Avon. A whole other set of difficulties.