The first British Military Hospital in Singapore was built in 1909 on Sentosa Island, then known as Pulau Blakang Mati. In 1912 this was closed and a new hospital erected at the Tanglin Barracks on the main island of Singapore. The building on Sentosa was later converted into an educational centre. Today, the building houses the Pioneers of Singapore Museum and the Surrender Chambers.
The increase in troops in the years preceding World War II called for a larger hospital for British military personnel and their families than could be provided at Tanglin Barracks. Thus, in 1938, construction began on a military hospital in the Alexandra cantonment. The designated site was a 32 acre (12 hectare) plot of land near the railway tracks and the Ayer Rajah Road (the present day Ayer Rajah Expressway). Ayer Rajah Road then was only a track and what is Alexandra Village today was a row of shops and attap shanties which sprang up to serve the needs of the hospital staff. Quarters for the staff were first built across the railway line in Alexandra Park. Eventually the Officers Quarters and Mess, Nursing Sisters Quarters and Mess, and various other support buildings for the hospital were built in Alexandra Park.
Alexandra Military Hospital was designed and constructed by a team of Royal Engineers, supervised by Chief Draughtsman Major J.W. Colbran. An article from The Straits Times in 1940 described the hospital as "the most up-to-date and one of the largest military hospitals outside Great Britain." The main block of the hospital was built to accommodate 356 beds with various medical, surgical and officer wards. The building was long, with three storeys and a basement. A number of ancillary buildings were also constructed: the barracks block, laboratory, mortuary and living quarters for staff.
According to Lloyd Hughes, one of several members of the staff in 1940 still living today, "the foundations were started in late 1938, but the building itself was not completed until well into 1939...This included the accommodation block, that is, the barrack rooms and married quarters, also other buildings for cook-house staff and a sergeant's mess...in all, the Alexandra Hospital was quite a big job."
The hospital opened in 1940 when the 32nd Company of the Royal Amry Medical Corps (RAMC) transferred from the smaller Tangling barrack hospital. Additional staff of approximately 30 Queen Alexandra Nursing Sisters did not arrive until late 1940. As Lloyd Hughes puts it, "we were pleased to see them!"