Mr Gregory Thomas

Mr Gregory Thomas is a consultant colorectal surgeon at St Mark’s Hospital, the United Kingdom’s only specialist gastrointestinal centre, a post he has held since 2020. His caseload serves the diverse population of north‑west London while also accommodating a substantial volume of tertiary referrals from colorectal units across the country. In addition to his dedicated colorectal practice, Mr Thomas contributes to the emergency general‑surgery service at London North‑West University Hospitals, handling acute presentations such as bowel obstruction, perforation and gastrointestinal bleeding.

Prior to joining St Mark’s, he served as a consultant colorectal surgeon at Ashford and St Peter’s NHS Trust from 2018 to 2020. He is an honorary senior lecturer at Imperial College London, he has authored more than 70 peer‑reviewed articles and delivered invited lectures at numerous national and international conferences, maintaining a particular research focus on pelvic‑floor disorders. He is a Fellow of the Association of Coloproctology of Great Britain and Ireland (ACPGBI), chair of its Proctology Sub‑Committee, a member of the European Society of Coloproctology, the UK Pelvic Floor Society and sits on the council of the Coloproctology Section of the Royal Society of Medicine.

Mr Thomas’s clinical portfolio encompasses both elective and emergency colorectal surgery. His emergency expertise includes management of bowel obstruction, perforation, appendicitis, diverticulitis, gastrointestinal haemorrhage and mesenteric ischaemia/infarction. In the elective arena he focuses on pelvic‑floor disorders (rectal prolapse, faecal incontinence, chronic constipation), the sequelae of pelvic‑floor surgery and post‑obstetric injury complications. His proctology practice addresses anal fistulae, fissures, skin tags, haemorrhoids and abscesses. He also manages complex abdominal‑wall pathology, including groin and complex ventral hernias, and provides comprehensive stoma care (colostomy and ileostomy). Although his primary interest lies in non‑malignant disease, he participates in bowel‑cancer diagnostics and maintains expertise in diverticular and pilonidal disease, as well as other broad areas of colorectal surgery.

Mr Thomas’s research programme is centred on pelvic‑floor disorders, pilonidal disease and proctology. He supervises MD students from Imperial College.

Mr Thomas currently serves as Chair of the Proctology Sub‑Committee of the Association of Coloproctology of Great Britain and Ireland (ACPGBI). He organises courses for senior trainee and consultant surgeons. This leadership role underscores his commitment to advancing standards of care and education in proctology.

To date, Mr Thomas has authored more than 60 peer‑reviewed papers in leading journals, including Colorectal Disease and The British Journal of Surgery. He has also contributed chapters to major textbooks on colorectal surgery and serves as a regular reviewer for international surgical publications.

Mr Thomas graduated from St Mary’s Hospital (Imperial College London) where he completed both a student research degree and a postgraduate research doctorate, each conducted within Imperial College’s Department of Surgery. He subsequently trained in colorectal surgery at hospitals in London and Surrey, followed by a post‑graduate fellowship at St Mark’s Hospital before his appointment as a consultant. Complementing his UK training, he undertook overseas observerships and fellowships in the Netherlands, the United States and France, acquiring expertise in advanced minimally invasive and functional colorectal techniques. At St Mark’s, Mr  Thomas organises postgraduate teaching programmes, including hands‑on workshops, journal clubs and simulation sessions for senior trainees and junior consultants. He also mentors the many overseas surgeons who undertake short‑term observerships at the hospital, providing clinical supervision and academic guidance. In addition, he is a regular invited lecturer at national and international meetings where he shares his clinical and research insights with a global audience.