Mary Elizabeth Cairns was born on 9 March 1906 in Rossland, British Columbia. She was the oldest of two daughters born to Thomas Picton Rogers, formerly of Prince Edward Island and Elizabeth Sophia Hyland Scheel. For a time she worked as a dressmaker and then enrolled in nursing training at the Vancouver General Hospital, receiving her R.N. in 1941. Following graduation she did post-graduate work at the Royal Victoria Hospital in Montreal. On 10 June 1946 she married R. Louis Cairns of Freetown, P.E.I. and settled down to life on the farm. She was an industrious worker in her commuity and in the Freetown United Church in particular where she was a C.G.I.T. leader, Sunday School teacher, and assistant church organist. In addition to being associated with the Village Croft House in Bedeque and making quilts, she continued to pursue her lifelong hobbies of painting, nature study and photography.

Introduced at a very early age to photography by her mother who took and developed her own photographs she began taking photographs with a prized gift, a 116 Box Kodak. In her final nursing year she was photographer and coordinator for her class yearbook. During her early years on the farm with no lights and little money, she devised her own enlarger from materials at hand. Later she was instrumental in forming the Freetown/Bedeque Camera Club whose members developed films, made prints and produced their own Christmas cards. Cairns was a member of the Photographic Society of America from 1961-1982, submitting many photographs to competitions and receiving many "honorable mentions". She was also a member of the Colour Photographic Association of Canada where her special interest in nature photography earned her the rating of 2nd. Star Exhibitor of Natures Studies. This rating meant that she had had 36 acceptances in international slide exhibitions.

Following the death of her husband in 1978, she moved to Summerside where she died in the Prince County Hospital on 29 December 1986.