The first ideas for this institution may have emerged from the Oxford Hotel at the corner of King and Phillip Streets, a regular meeting house for the Royal New South Wales Lancers.
The objects of the Club were stated as: According to a fund-raising document issued in 1919, the qualifications for ISC membership were “Commissioned rank in HM Naval or Military Forces, and Active Service in a War of the Empire”.
The results of the appeal for funds are unrecorded, other than a list of donations including £2000 from the State government and £400 from the Australian Jockey Club.
On 19 March 1932, Francis Edward de Groot, described by the Sydney Morning Herald as "an officer of the New Guard", rode past Premier Jack Lang and cut the ribbon on the Bridge, shouting "I declare this bridge open on behalf of the respectable citizens of New South Wales".
In 1942, when the crucial role of the 2/17th Battalion in the Battle of El Alamein was learned, ISC members from the 1/17th sent a message of congratulations to their successors.
Characters still fondly remembered by members today included Betty the cashier, who "knew everyone and everything", and Rupert the waiter, who was kept on even when he "got the shakes" in later life.
Celebrated regulars included Brigadier Sir F 'Black Jack' Galleghan, who had commanded AIF troops in Changi and later became deputy head of the Commonwealth Investigation Service (which evolved from the wartime Military Intelligence Bureau).
In April 1985 the Sydney Morning Herald reported a proposal by the ISC to the Union Club in Bent Street regarding a merger.
The voluntary liquidation of this company was begun in 1991, the first distribution of $1,700,000 being noted in the RACA President's Report of that year.
RACA's 100th year saw the opening of the newly refurbished ISC Lounge on the third floor of the Macquarie Street Clubhouse.