Thelma Afford was born Thelma Thomas, the only daughter of Mr and Mrs W.J. Thomas, in Broken Hill.
She was educated in Adelaide and was one of the first five teachers to introduce art into Adelaide's secondary schools. As well as teaching, she acted in radio plays for the Australian Broadcasting Commission and for the experimental Ab-Intra Studio Theatre, and later became well-known for her costume designs, including those for South Australia's 1936 Centenary Pageant. She lived in Sydney from 1937, marrying playwright Max Afford in 1938. In the years after her husband's death in 1954 she returned to teaching for another eighteen years, then undertook research on the history of the pioneering little theatres of Adelaide. When this failed to be accepted for publication she deposited a copy of 'Adelaide's Little Theatres - Their Dreamers and Visionaries 1900-1940s' in the Fryer Library of the University of Queensland.