What ensued was a most productive era. Professor McFadzean's vision, clinical and administrative ability, commitment to research and strong personality were the main factors which enabled the Department to take off to new heights, despite inadequate financial support. The period saw a rapid expansion of the University, the Faculty of Medicine and the Department. It was also a period when Hong Kong witnessed a phenomenal growth in its population. The University was the only tertiary institution in the territory until the establishment of the Chinese University of Hong Kong in 1963 and had the only medical faculty until the Chinese University established its faculty in 1980. Funding from the Government was secured through the University and Polytechnics Grants Committee. To meet the demand for doctors, the intake of students rose from 60 or so to around 150 a year in 1970. The Department of Medicine was responsible for the teaching of medicine in all three clinical years, but only 244 beds in Queen Mary Hospital were directly under the control of university clinical departments. It therefore had to spread its wings to other hospitals. Consultants in the government medical units of Queen Mary Hospital and other Government hospitals, such as Queen Elizabeth Hospital, Sai Ying Pun Infectious Disease Hospital and High Street Mental Hospital, as well as consultants in government subvented hospitals such as the Ruttonjee Sanatorium and Grantham Hospital were appointed as Honorary Clinical Lecturers to share the teaching. The Department was grateful to all these eminent Hong Kong doctors who provided not only their time and expertise but also their facilities, and for allowing their patients to be accessed for the teaching of medical students. This was the beginning of the Department's close collaboration with the medical profession outside the University. Other benefits from this arrangement became obvious as the years went by. It laid the foundation for the development of postgraduate professional training, both basic and in the medical subspecialties, and the Department was in a position to play a leading role in the process. 

Whilst a senior lecturer at Glasgow University, A J S McFadzean became interested in haematology, on which subject he published a number of original and important papers. After his arrival in Hong Kong, he continued to pursue this interest. He also directed his attention to chronic liver diseases: cirrhosis and carcinoma of the liver both being very prevalent in Hong Kong. His intellectual curiosity was contagious. Before long, all members in the department were engaged in research and some registered for the MD degree. Professor McFadzean realised that in clinical departments, teaching, research and clinical service must go hand in hand, and that in the pursuit of excellence all three must receive adequate attention. As leader of the only academic Department of Medicine in the territory, he also realised that the time had come to develop the medical subspecialties. This would provide appropriate teaching and clinical services, to train future leaders in the profession, and to put Hong Kong on the world map of medicine through its research achievements. To accomplish this, it was first necessary to train junior staff in specific subspecialties at renowned overseas centres. Naturally, in the early years most were sent to Scotland and England and later many were sent to the USA and Australia. In addition to haematology and gastroenterology, junior staff were trained in cardiology, endocrinology, immunology, nephrology, and respiratory medicine.