Receiving his final education at Andersonian University,[1] Allan started his working life as an apprentice draper to Daley & Co. in Glasgow before arriving in Australia in 1879.

[5] During his time in parliament, Premier William Kidston was known to seek Allan's advice on financial policy.

In 1917 he was appointed honorary chief commissioner, treasurer, and chairman of the London executive committee of the YMCA army and navy work abroad.

[2] He also took a keen interest in literature, authoring "A holiday ramble in new Zealand" and in 1915, he edited "Letters from a young Queenslander" and "Mesopotamia and India", the latter two being written by his son, Robert Marshall Allan about his experiences during World War I.

[2] On 4 June 1885, Allan married Eliza Balloch Stark at South Brisbane[7] and together had two sons and two daughters.