He was among the most renowned mountaineers from the late 19th century to the early 20th century, known for numerous first ascents in areas such as Jotunheimen and Northern Norway.
[1][2][3][4] Priestman participated in numerous expeditions in Norway alongside notable mountaineers such as William Cecil Slingsby, Harold Raeburn, Kristian Tandberg, George Wegner Paus, Geoffrey Hastings and Therese Bertheau.
Aside from his mountaineering activities, Priestman was known for his extensive collection of photographs depicting the early history of Norwegian mountaineering in the late 19th century, as well as his systematic work in cartography, focusing on mapping the mountains.
[6] He also developed an interest in scientific work related to the use of wool and later established his own consultancy in the textile industry.
In 1914, he served as an advisor to the War Office on military clothing and became a technical consultant for the British Research Association.