Aubrey "Po" Powell and Storm Thorgerson were once known as "Hipgnosis".     It is not an exaggeration to say that their collective was responsible for much of the significant album cover artwork of the 1970's.     This includes Wings from "Band on the Run" through "Back to the Egg", and Aubrey Powell would continue on-and-off with McCartney through "Off the Ground" and his 1992 World Tour.