Born in Ceres, Fife to ploughman Richard Sleath and Mary Fernie, he migrated to Queensland in 1877, becoming a shearer and prospector.
He helped found the first Socialist League at Broken Hill and was a member of the central executive of the Labor Party in 1898.
In 1894 he was elected to the New South Wales Legislative Assembly as the Labor member for Wilcannia.
He lost his Labour endorsement in 1901 but was re-elected as an Independent Labor candidate, losing his seat in 1904.
This article about an Australian Labor Party member of the Parliament of New South Wales is a stub.