William Murdoch was born in Lugar in August 1754. He was the son of John Murdoch, a millwright who leased Bello Mill from the local laird, James Boswell.
At school he excelled in mathematics, while he learned his practical engineering by helping his father. In 1763 the nine year old William helped his father build a "wooden horse", a tricycle driven by hand cranks. It is said that in 1774 he helped his father build Craikston Bridge over the Lugar Water.