Percival WMS S NT348986 1 385 40m
Perceval 1856 OS 6 inch 1st edn.
Percival 1899 OS 1 inch 2nd edn.
This is a renaming, proabably on grounds of politeness, of Backside, which appears as such on Roy (1753), Ainslie/Fife (1775) and SGF (1828). I have not been able to ascertain who the eponymous Percival was, and the OS Name Book is no help here.
This place-name appeared in printed volume 1