At the outbreak of the Second World War, Hodgkinson was working for the Herald newspaper in Melbourne. In May 1940, he enlisted in the army (service no. VX18229) and was posted to 7 Division Headquarters. By October, he was in the Middle East. Serving in the Syrian Campaign in 1941, he was also promoted to sergeant and worked as the assistant editor on the Australian War Memorial's first army Christmas Annual, Active Service. The black and white illustrations were often lusty renditions of Australian soldier exploits in the Middle East while on leave, and these are now in the Memorial's art collection.
Hodgkinson spent much of 1942 and 1943 serving in New Guinea on the Kokoda Track and was mentioned in despatches in 1943 for conspicuous gallantry. He was promoted to lieutenant in 1944 and took charge of 7 Military History Field Team, which was responsible for coordinating the collection of information and objects for the Memorial. During this time, Hodgkinson continued to find time to paint and draw the men and activities around him, as with Owen Stanley trail. In March 1945, he was appointed an official war artist.
Hodgkinson's tenure was relatively short in comparison to other artists, and limited to a single theatre of war. He was attached to 7 Australian Division and sent to Morotai in May. After several weeks at sea, he took part in the amphibious assault on Balikpapan, Borneo, in July 1945. The works he painted around this time capture the troops' sense of frustration at the weeks of enforced inactivity onboard a transport vessel, and in contrast the frantic energy of the events at Balikpapan. As an official artist, Hodgkinson placed himself on the front line. This is borne out in the immediacy and veracity of his works depicting the Australian infantry in close contact with the enemy as they fought their way inland.
One of Hodgkinson's most prolific and flourishing periods of art production was during his service as an official artist. He completed and forwarded to the Memorial some 70 paintings and drawings; however one shipment of 12 pieces and over 70 drawings and sketches were stolen on their arrival in Atherton, North Queensland.
After the war, Hodgkinson travelled to Europe to study art; and, following a few years back in Australia, later took up residency in Spain. His interest in landscape saw him revisit Papua New Guinea and resettle in Australia at the end of 1970.