It was at a school concert that he heard older pupil Geoffrey Richardson (later joining progressive rock group Caravan) performing the folk blues of Bert Jansch and Jackson C. Frank, inspiring St. Clair to take up the guitar.
St Clair's television debut was on ITV's New Faces on his birthday in 1974, singing one of his own songs, "So Many Empty Mornings'".
That same year he headed south for London and a professional life as a singer-songwriter, playing in wine bars and restaurants.
During this period he formed a folk-rock band called Millstone Bill with old friend Steve Southorn; they played pub and club venues around the Midlands.
St Clair set up home in North London; by this time being booked to play in Italy, the Netherlands and the Republic of Ireland as well as all over the UK.
Street Theatre became popular and St Clair enjoyed this freedom to perform in towns and cities throughout Europe.
It was during this period that he performed alongside comedians such as Eddie Izzard, Sarah Crow and Ann Bryson (then known as the Flaming Hamsters).
He played at a Barry Manilow concert at Blenheim Palace, and in 1988 St Clair performed to 5,000 people at the Festival of Voices in the Wembley Conference Centre.
St Clair was introduced to music journalist John Tobler by Dave Cousins of the Strawbs.