Her postgraduate work took her throughout Europe where she further specialised in gynaecology and obstetrics, becoming a
Licentiate of Midwifery in Ireland in 1901. Her first position was as a
house surgeon at the Samaritan Hospital For Women in Glasgow in 1900, followed by Gynaecological Surgeon at the
Victoria Infirmary in Glasgow from 1906 to 1910. She continued her studies, gaining a
DSc from the University of Glasgow in 1910. In 1911 she took up the position of First Assistant to
Professor J. M. Munro Kerr, who held the Muirhead Chair of Obstetrics and Gynaecology at the university. During her time in Salonika she established a nurses training school for Serbian girls and oversaw the establishment of the only
orthopaedic centre in the Eastern Army. She finished her war service as a surgeon at a
Royal Army Medical Corps hospital in
Constantinople.
Dr Halliday Sutherland heard her talk and he later quoted her in his 1922 book "Birth Control". When
Marie Stopes sued Dr Sutherland for libel over remarks in the book, McIlroy became a witness for the defence. She retired in 1934, in her own words
to gain a few years of freedom although she continued private practice at
Harley Street and other hospitals and clinics throughout London. At the outbreak of the
Second World War she came out of semi-retirement to work as a consultant for the maternity service at
Buckinghamshire County Council. She was also the senior obstetrician to the Maternity Hospital for the Wives of Officers, Fulmer Chase. She was active in several professional medical associations: her interest in medical legal matters culminated in her becoming President of the Medico-Legal Society of London; at the
British Medical Association (BMA) she was vice-president of the Section of Obstetrics and Gynaecology in 1922, 1930 and 1932; a member of the
Representative Body from 1936 to 1939; a member of the BMA Council from 1938 to 1943, President of the BMA Metropolitan Counties Branch in 1946 and she was also president of the Section of Obstetrics and Gynaecology of the Royal Society of Medicine. ==Publications==