It appears that the designer of the MMTB Roll of Honour was a young artist of growing reputation, who became well-known as a water-colourist and draughtsman. In 1922 he toured abroad, including the Middle East, and his art shows were well-patronised. In 1941 he was appointed as a War Artist to accompany troops to the Middle East. The illustration above dates from that appointment, and was included in the book Active Service: with Australia in the Middle East. He returned after a few months saying that he felt younger artists would be more suitable. He had struggled in the hot temperatures with the heat drying out his water-colours too quickly. Herbert died in 1945 aged only 52 "after a long illness", so one might surmise that he had been unwell during his time with the 2nd AIF.
I have created a commemorative online database of the WW1 volunteers of Essendon and Flemington in Victoria, with a blog to support the website: see link below.
I have other websites and blogs which follow other interests.