William was born in 1850, the son of shepherd Alexander MacMillan and Isabella MacLeod of Ardennish, Lochportain. His father was originally from Berneray, and returned there with his family whilst William was still a young boy, to a new building at Ferry.

William became a general labourer and farm servant, marrying Catherine Shaw of Backhill in 1890. They were to have six children together. He became a shepherd, like his father.

William was passed the house at Ferry following his parents’ deaths, and, in 1900 was allotted 22 Borve (Sandpoint). He earned a living as a fisherman and crofter. Islanders paid frequent visits to use his quern in order to grind barley into meal.