	After qualifying, Winner worked at the Elizabeth Garrett Anderson Hospital, the Mothers' Hospital in Clapton, and the Maida Vale Hospital for Nervous Diseases. In 1940, during World War II, she joined the Royal Army Medical Corps, where she was promoted to the rank of lieutenant colonel. She was appointed an Officer of the Order of the British Empire (OBE) in 1945. Winner also later served as the consultant to the Women's Services from 1946 to 1970. After the end of the war and on the eve of the emergence of the National Health Service, Winner joined the Department of Health in 1947 as its first female deputy chief medical officer, a position she would serve in for the next twenty years. In 1959, she became a fellow of the Royal College of Physicians. Between 1965 and 1968, she was a honorary physician to the Queen. In the 1967 New Year Honours, Winner was appointed as Dame Commander of the Order of the British Empire (DBE). She was also appointed as the Linacre Fellow of the Royal College of Physicians, a position she held from 1967 to 1978. While serving in the position, Winner played a key role in developing postgraduate medical training posts for the Joint Committee on Higher Medical Training.