Morcom was born Sidney Morcom in Borrolool, Northern Territories, to an Aboriginal family. At one week of age he became one of the Stolen Generation, (see: Australian Aboriginal and Torres Strait Islander Children). He was forcibly taken from his parents and sent to the Garden Point Mission, Melville Island, where his name was changed to Luke (all children were assigned Biblical names), he was separated from his sister Flo, and spent the next 12 years there, until he was fostered by an English immigrant couple, Jack and Maimi Smith, near Adelaide.
In 1972 he moved to Darwin, where he is now a recreation officer and poet.