Thomas was born in Ranikhet, British India, to Charles D'Arcy Bingham and Bertha (née Birkbeck).
[1] She was sent back to the United Kingdom as a child, where she lived with relatives and attended the Berkhamsted School for Girls in Hertfordshire.
[1] After leaving school she trained and worked as a shorthand typist, and in 1935 joined the National Gallery in London where she worked for Kenneth Clark, then its director.
[2] Thomas was among the few women who worked in production at the BBC's Lime Grove Studios during the 1950s.
[2] Thomas produced programming presented by David Attenborough and Huw Wheldon.