Moore was born as Mary Gwendoline Lloyd in Tredegar, Blaenau Gwent, Wales, United Kingdom, on 2 December 1911. Her claimed date of birth was inconsistent in different reports (27/28/29 November 1911). She had four siblings, including Sarah Lilian. Her father was a coal miner.
Moore’s first marriage was to Cyril Clifford Pearce. The couple had a son, Brian Eugene (aged 80 in 2022), and two daughters, Joan (aged 92 in 2022) and Jill (aged 78 in 2022). Her husband died at the age of 37; she later remarried.
In 1966, Moore emigrated to Australia to live with one of her daughters who had previously moved there. She returned to Wales for a family visit and at that time she persuaded her other daughter to move to Australia as well. Her son remained in Tredegar with his wife.
At the age of 93, Moore underwent surgery to have a triple bypass after having mini strokes. Around the age of 109, she lost her eyesight. In 2022, she had 8 grandchildren, 9 great-grandchildren and 3 great-great-grandchildren.
Moore died at the Bribie Cove nursing home in Bongaree, Queensland, Australia, on 31 March 2023 at the age of 111 years, 119 days.