Rayner was born in New Zealand, like her mother, Rhona Blanche (née Duckworth). She was born in
Dunedin in 1900. Her father Frederick Richards Rayner was an artist who had been born in Wales. On 16 May 1907, her sister, Betty, was born and they would spend their lives mostly together. The family's finances varied and when there was sufficient money she and her sister received a private education. She went to England to study social work where she re-met her godmother
Constance Smedley. Smedley had original ideas about theatre and had started the
Greenleaf Theatre – she visualised a "A universal travelling theatre, directly in contact with the community". After Joan met Smedley she decided to study the theatre and acting instead. She returned home and she enthused her younger sister. In 1925 they both went to work at Smedley's Greenleaf Theatre where they both learned about acting. They travelled in France and Germany, but by 1929 they were back in Sydney creating a youth theatre and being pictured with their caravan. (having fallen out with Smedley.) They returned to tour Europe and in Britain they used another of their caravans to take their theatre to English villages. In the
1978 Queen's Birthday Honours, she was made a member of the
Order of Australia because of her work for children's theatre. ==Death and legacy==