Born with spina bifida, St John had been performing since childhood and made his first appearance on radio at the age of 8. By the age of 15 he could be seen on a TV talent show and in the mid-60s joined Sydney group The Syndicate.
Became the first Australian artist to sign to the US Asylum label and reached the Top 10 in 1977 with 'Fool In Love,' written by Frankie Miller and Andy Fraser.
On 18 October 2000, the wheelchair-bound St John was on the main podium at the opening ceremony of the Sydney Paralympic Games, singing the national anthem.