Mary Barnes was born and raised in Portsmouth, England, and educated at home and at local schools. She trained as a nurse and joined the British Army during World War II, spending a year working in hospitals in Egypt and Palestine. She suffered her first mental breakdown in 1952, and was diagnosed with schizophrenia. In 1965, at age 42, she entered Kingsley Hall for regression therapy with R.D. Laing and Joseph Berke. During the process, she discovered a talent for art. She co-authored a book about her therapy with Dr. Berke, and became a noted painter, taking her works on tour worldwide, accompanying by talks on her experiences and mental health. In 1979, a play based on her life was broadcast on BBC Radio in the UK. In 1989, she published Something Sacred, a volume of conversations, writings and paintings.