Since the 1970s, she has worked on numerous New Zealand television dramas including Close to Home, Homeward Bound, Duggan and Marlin Bay.
She is a former deputy chair of NZ On Air, and together with her husband Brian Edwards runs a media training consultancy company.
[1] She worked on almost 200 scripts for the soap opera Close to Home, and other shows she wrote for in the 1970s and 1980s included Gloss, Country GP, Open House and Peppermint Twist.
[3] In 1982, she wrote the television drama Casualties of Peace, inspired by her father's experience, which was nominated for best script at the New Zealand Feltex Awards.
[1][7] A review for the Evening Post described it as an "easy read, good natured, practical and encouraging", although noted that the book "is full of what most of us would regard as common sense".
[10][11] They were credited for converting her into a capable television performer, including by encouraging her to soften her voice and ensuring that she appeared serious or smiled when appropriate.
[18] In the 2001 Queen's Birthday Honours, Callingham was appointed a Companion of the New Zealand Order of Merit, for services to drama.