The Glasgow-born actor was cast in Grange Hill after attending a London stage school from the age of nine where he studied alongside EastEnders' stars Patsy Palmer and Sid Owen. After appearing briefly in an ITV sitcom called Now and Then (1983), Alford landed the role in Grange Hill (1978) at the age of 11. But the young actor found fame too tough to handle and started drinking heavily. By the time he left the show at the age of 17 he had reportedly spent up to £80,000 on alcohol and gambling.

John, most famous for his role of young fireman Billy in the hit TV series, London's Burning (1988), became an overnight pop star with reggae version of the song "Smoke Gets In Your Eyes" which went into the UK charts at number 13 in 1996. In December of that year, just before he was due to appear in pantomime in Sunderland, Alford collapsed and was taken to hospital in Newcastle suffering from a rare blood disorder.

In May 1999, he was jailed for nine months for supplying drugs to an undercover Journalist. After the drug charges and sentence John found TV work extremely difficult to find and became a roofer. The following year he appeared in Mike Bassett: England Manager (2001), playing the part of Deano.