Mansfield began her career at the
Royal Liverpool University Hospital, and became a consultant vascular surgeon there in 1972 and later a lecturer in surgery at the University of Liverpool. She then moved to London in 1980 to work at
Hillingdon Hospital. Two years later, she was appointed by
St Mary's Hospital in
Paddington as a consultant vascular surgeon. She remained at St Mary's for the rest of her career, while also serving as an honorary consultant in pediatric and vascular surgery at
Great Ormond Street Hospital. In 1993, she was made a professor of vascular surgery at St Mary's Hospital, making her the first female professor of surgery in the United Kingdom. In May 2018, she received the NHS Heroes Award. She was promoted to
Dame Commander of the Order of the British Empire (DBE) in the
2023 Birthday Honours for services to surgery and equality in medicine. ==Personal life==