After Sir Henry's death in 1897, Ayers House's important place in South Australian history and society did not cease. During the 20th century it had a variety of "uses and users" which has seen it enjoyed and utilised by a wide cross-section of South Australia's population.
Following a period of inoccupancy subsequent to Sir Henry's death, the house and grounds were sold off to become 'a pleasure resort' known as Austral Gardens. They included an open-air theatre and the Palais de Danse - later the Palais Royal. During and immediately after the First World War it was a club for the Returned Soldiers and Sailors Imperial League (RSL).
In 1926, the property was purchased by the State Government under whose ownership it has remained until the present day. For over 40 years until 1969, it was used by the Royal Adelaide Hospital as a nurses' residence and training school. It was during this period that much of the intricate hand-painted detail and stencilled decoration on walls and ceilings was hidden with layers of white paint.
In 1970, Ayers House underwent major change and refurbishment, when the building including the stables area was structurally altered to accommodate a restaurant and function centre. The other half of the property was dedicated as a historic house museum and the National Trust of South Australia was invited to administer this function and take up office space within the building. Although National Trust headquarters were relocated from Ayers House in the mid 1990s, the National Trust has remained committed, with the assistance of a dedicated group of volunteers, to the ongoing management and interpretation of the historic house museum at Ayers House.
