He studied drama at the BDL (British Drama League) and in Richmond, Surrey, with no intention or pretension of turning professional. He had a passion for racing motorcycles and cars (bottom rung of the ladder) and became a director of the once-famous Chequered Flag of Chiswick which specialised in selling sports and sports-racing cars. "The Flag" also made the Formula Junior Gemini. Acting was a passion for the evenings and weekends. Most significant influence was being directed and coached by Paul Gillard. St John emigrated to Canada in 1967 where he learned something of the techniques of acting on camera by giving his services to cinema students at Concordia University. Appearance in one of these gems followed by a stage appearance as Sowerberry in "Oliver" led to an offer by a leading agent. He is now a loyal member and staunch supporter of ACTRA. He is best known for turning up on location riding his Ducati 900 SP.