Robert Bell Hamilton was 23 years old and practising as an architect when he enlisted on 8 December, 1917. At the time, he was a single man and living with his mother, Jane Napier Hamilton (nee Bell), at 91 Powlett St, East Melbourne. He had been educated at Scotch College. He was 5' 9" tall, with brown eyes and hair. He began training at Broadmeadows in 20 March 2018 and was attached to the 11th General Reinforcements, with further training from 1/7/1918 - 30/8/1918. on 31 August, the 11th Reinforcements left for England on board HMAT A37 Barambah. On 13 October, having landed in England, Robert Hamilton was in hospital, suffering from Influenza and Mumps. He finally got to camp on 14 November 1918, three days after the war had ended and was attached to the Reinforcements 14th Battalion, where he remained for most of 1919. With the war over, he was granted leave with pay and subsistence, with the dates of leave being from 2 December 1919 to 27 January 1920. 

Robert Hamilton did not waste his time: he found a position with Slough Urban District Council as an Assistant Architect and continued to draw pay from the army into 1920. His discharge from the AIF came on 31/2/1920,  so he was asked to reimburse 157 poounds, as he was 'in non-military employment'. Allotted to sail home on 17 July, Hamilton wrote asking that he be allowed to spend time in the USA to pursue his studies.

Robert Bell Hamilton used his time overseas well. On his return to Australia, he set up practice and in 1927 had rooms in the Metropolitan Building at 94 Queen St., Melbourne. The earliest Electoral Roll shows him living in Ferntree Gully in1924, but by 1925, he had moved to Toorak, and with his wife Olive, was domiciled at 76 Clendon Rd. He became a notable Australian Architect and was considered 'Victoria's foremost practitioner in the interwar Old English/Tudor Revival style'. A Heritage Citation Report by the City of Stonnington stated that he was the architect of eleven different luxury apartment blocks in Toorak in the 1930s. He served as a Councillor on Prahran Council in the 1930s and in 1940, served on the Mornington Council. In November 1945 he was elected as Member of the Legislative Assembly for Toorak for the Liberal Country Party. he did not live long enough to serve out his term, dying on 15 May 1948 at the Mornington Nursing Hospital. He left a wife, two sons and a daughter.