Clayton-Thomas began his music career in the early 1960s, working the clubs on Toronto's Yonge Street, where he discovered his love of singing and playing the blues.

Clayton-Thomas was born in Kingston upon Thames, Surrey, England, the son of Fred Thomsett, a decorated Canadian soldier of World War II.

By the time Clayton-Thomas was fourteen, he had left home and was sleeping in parked cars and abandoned buildings and stealing food and clothing to survive.

He was arrested several times for vagrancy, petty theft, and street brawls and spent his teen years bouncing in and out of various jails and reformatories, including the Burwash Industrial Farm.

Rhythm & blues migrating up from Detroit and Chicago was the music of choice on the strip, and Arkansas rockabilly pioneer Ronnie Hawkins recognized the formidable talent of the young 'Sonny' Thomas and took him under his wing.

He immersed himself in the local jazz & blues scene dominated by the likes of John Lee Hooker, Joe Williams, Sonny Terry and Brownie McGhee, Lenny Breau, Oscar Peterson, and Moe Koffman.

Folk singer Judy Collins heard Clayton-Thomas one night at a club uptown and told her friend, drummer Bobby Colomby, about him.

Bobby's band, Blood Sweat & Tears, had broken up four months after releasing its debut Columbia album, Child Is Father to the Man.

Blood Sweat & Tears' Greatest Hits album has to date reportedly chalked up over seven million copies in worldwide sales.

[citation needed] Blood, Sweat & Tears headlined at major venues around the world: the Royal Albert Hall, the Metropolitan Opera House, the Hollywood Bowl, Madison Square Garden, and Caesar's Palace, as well as the Newport Jazz Festival and Woodstock.

It was the first contemporary band to break through the Iron Curtain with its historic United States Department of State-sponsored tour of Eastern Europe in May and June 1970).

In the early years Clayton-Thomas lived on the road, travelling all over Europe, Australia, Asia, South America, the US, and Canada with Blood, Sweat & Tears.