For the first time since the occupation of the new building in 1957, substantial new building activities, other than the fitting out of vacant wings for Physical Biochemistry and Genetics, were carried out in 1967–73.
A special building for breeding specific-pathogen-free rats and mice, located to the west of the main Animal Breeding House, was commenced in 1971 and completed in 1972, but because of difficulties with the mechanical services it was not commissioned until early 1973.
In 1968, a Radioisotope Suite, with chemical laboratories and rooms for handling with safety large and small animals that had been inoculated with highly radioactive materials, was built on the eastern end of what had been the lawn-covered roof of Wing F, the Experimental Pathology/Immunology animal house. Also, on the ground floor of the same building, a well-equipped Animal Hospital was constructed, with operating theatres for large and small animals.
In 1957, the Library, on the top floor, occupied the area east of the passageway connecting the front and rear wings and there was a small open balcony extending towards the west. By 1970, the balcony had been converted to library space extending 6 metres to the west, and the Common Room, in the corresponding area on the ground floor, was also extended. The additional space on the floor level below this was used for storage space, a School Computer Centre and a seminar room.
Just as laboratories had been constructed on the roof on Wing F in 1968, in 1972, laboratories to accommodate the Department of Human Biology were built on the lawn-covered roof of Wing E, the Animal House for Infected Animals. The layout of the laboratories was designed by Kirk with advice from Boyden. In addition to laboratories and studies, a Seminar Room and adjacent space which served as a coffee room were provided.