Trevor Duncan (real name Leonard Charles Trebilco) was born in Camberwell, London, England, on 27 February 1924. By the age of twelve he could play by ear, but two years later he wanted to learn to read music and study a technical analysis of what he was doing by instinct. He gained this knowledge at Streatham Library where he found books by academics, and full scores to examine. For a year he attended the Trinity College of Music for an external course on violin, harmony and counterpoint.