John Cazabon

Cazabon was born in Hertford, Hertfordshire, to violinist and composer Albert Cazabon (1883–1970) and Norah Cazabon née Delaney, a professional actress born in Australia. He had an older sister Norah Cazabon and a younger brother Robert Brendan Cazabon (born c. 1919), who was killed in action in 1941.

In 1927 the family moved to Sydney, where Albert Cazabon had secured the post of musical director to the Prince Edward Theatre's orchestra, and Gladys, née Curtin, a professional actress born in Australia. Cazabon and sister Norah were members of Sydney's Impressionist Theatre in 1933 and in 1934, with their mother, joined the Independent Theatre and Pickwick Theatre Group, both run by Doris Fitton. They later joined Beryl Bryant's group.

Albert Cazabon returned to London in 1936, living at Aberdeen Place, and was hired by the BBC, but Cazabon stayed behind and secretly married actress Margery Gielis of Toowoomba. They had a son Charles who married Margaret Burns on 20 May 1967.

His sister Norah married Stephen Merivale of Middleton Hall, Leeds. Stephen was cousin of Philip Merivale who married Gladys Cooper.