This theory is based on the presumption that Kirkpatrick, late in his career, may have undertaken part of the commission and sought assistance from a younger architect - or may have, for reasons as yet unknown, been unable to complete the commission which was then taken over by E. A. Scott  The new house took on the name "Cliffbrook" and the earlier residence was subsequently known as "Gordon Court". Miller died in 1923 and the property was sold to Welki King before finally being sold to the Australian Government. During the Second World War the estate was occupied by the army to serve as a school of tropical medicine. After 1945, "Gordon Court" and part of the estate was auctioned and sold to Friedrich Schiller, a Hungarian, electrician who lived in, the mansion with his sister. "Gordon Court" was eventually sold in 1977 and promptly demolished to make way for housing development. The site as it stands today was purchased by the Commonwealth and housed the headquarters of the Australian Atomic Energy Commission (AAEC) from 1953 to 1981 (later renamed the Australian Nuclear Science and Technology Organisation) (ANSTO). The property purchase by the AAEC was not finalised until 1959, for the sum of $13,518.42. The period between 1953 and 1981 saw the most far reaching changes to the site. Three substantial buildings were added to the site. A single storey brick residence. a single-storey brick office building. and a 2-3 storey brick office building. Along with these were lesser buildings including two fibro buildings (which may date from the army's occupancy) and a small greenhouse. The exact dates of construction of three brick buildings are not known. Max Dupain's photographs of the site dated 1965 show that both the L-shaped brick office building and the single storey brick office building existed at this time and presumably too the residence. The photographs also show that in 1965 the present 2-3 storey L-shaped building comprised a single storey on its northern wing and 3 storeys on the eastern wing. This photograph also shows a mature Norfolk Island Pine in the space between "Cliffbrook" and the three storey wing. It appears from ANSTO records that the single storey northern wing of the L shaped building existed prior to 1958 when architects Budden Nangle and Michael designed the three storey eastern wing. The caretakers cottage was also designed in 1958. The Green house was erected in March 1959. The eastern wing although containing the equivalent number of storeys as today has been altered on its western and southern faces.