Malcolm Moncrieffe was born in Perth, Scotland, and immigrated to the United States with his older brother, William, in the 1890s. Moncrieffe settled in Big Horn, Wyoming, where he established a business raising sheep and cattle. He also played an important role in bringing the sport of polo to that area by creating a polo field on his property and taking part in importing and breeding horses for the sport.
From the guide to the Malcolm Moncrieffe letter, Moncrieffe (Malcolm) letter, 1930, (Redwood Library and Athenaeum)