Dr Mary McStay qualified at the medical college of St Bartholomew's Hospital London in 1 994. She completed her preclinical medical training at Cambridge University where she obtained an Honours degree in Pharmacology. Dr McStay completed her specialist training in Gastroenterology in London and spent two years in full time research at the Neuroendocrine Tumour Unit, Royal Free Hospital, London.

She was awarded a Doctorate of Medicine degree in 2005. In addition to clinical practice in general gastroenterology, she has a specialist interest in small bowel and colon capsule endoscopy and in the management of patients with Neuroendocrine tumours. She leads the Neuroendocrine tumour service at ESNEFT and is a Bowel cancer screening accredited Colonoscopist.

She is principle investigator in a number of clinical trials and East of England Representative for the British Society of Gastroenterology Clinical and Service Standards Committee.