Duncan was born in 1827, the son of Roderick MacLeod and Marion Campbell of Pabbay, then Borgh Mhor, Harris. He became a crofter and cooper of whisky barrels, like his father.

Duncan married Ann MacLeod of 7 Ardhasaig, Harris. With Ann he had a son, Roderick, who died young. Ann died shortly afterwards. Duncan continued to live in Ardhasaig for a time, before in 1862 obtaining croft 16 Ruisgarry (Brusda) on the island of Berneray. There he made his home with his second wife Catherine Paterson. Together they were to have six children.

Following Duncan's death in 1901, the croft was passed to his son Donald John.