From the book "Led Zeppelin, heaven and hell"
page 120/122
The old man on the cover was chosen, or made up, to bear a remarkable resemblance to one George Pickingill. Also in the background of the photo there is a blue haze that some argue is significant.
Who was George Pickingill? He was one of the most famous occult masters in England in the early 1890s. Pickingill came from Canewdon County in the Essex area of england and ruled the district like a feudal lord. He was nicknamed "Old George" and the oldest villager at the time of Pickingill's death said that Pickingill had always looked the same. He carried a carved walking stick with him and villagers believed that he could curse someone with just a touch of the stick. He was revered by students of the occult who came from all over Europe to learn witchcraft from him.
One of these students was Allan Bennett, who later tought his knowledge to aleister Crowley. some students even suggest that crowley met Pickingill back in the 1880s. Pickingill died in 1909 when according to local legend, his home was struck by lightning.
The photograph was shot at a photo session in early 1972, so it was clearly not an actual photo of Pickingill (in a 1971 intervieuw, though Page claimed the photo was one that he and Plant had found intact in a junk shop in Reading)
Only a couple of photographs of Pickingill are known to exist and whether jimmy Page planned the cover, or it was just coincidence, is a matter of debate but the man on the cover and Pickingill look identical.
The man is not Crowley, just google for images of Crowley and see for yourself,
also google for images of George Pickingill (or Pickingale)
(ps....there is no such thing as "Thelema House".....Crowley had an Abbey of Thelema in Sicily, the house he and later Page lived in is Boleskine House in Scotland, and it is a hotel at the moment, it was never torn down)
Do what thou wilt!