[1] During the war, the surrounding area of the Flagstaff House was known as Sime Road Camp, which is the Combined Operations Headquarters for the British Army and Air Force.

[1] During the fall of Singapore, Sime Road Camp was forsaken and shifted to the underground bunker at Fort Canning.

[1] After the British military completed their withdrawal, Flagstaff House became the residence of Singapore's Speaker of Parliament, Dr Yeoh Ghim Seng.

[1] Between 1996 and 1998, when the Istana underwent a major renovation, the Command House was the temporary residence of then president of Singapore Ong Teng Cheong.

Ong, who was an architect, played an important role in restoring the Command House and add a reception hall.