Alexander Milne was the son of Alexander Milne, a Scottish-born Master Mariner, and his wife, Alice Henrietta.

Alexander junior joined the High School from Ocean Road Elementary School in 1907, and left in 1910 to attend The Modern School.

This was a small secretarial school above a jeweller's in King Street, where Alexander learnt shorthand and "typewriting", and went on to be a junior clerk in the Quayside offices of Atkinson Bros.

In early 1915 he joined the Durham Officer Training Corps and received a commission as a 2nd lieutenant with the 3rd Durham Light Infantry.

He went to the front in 1916, and was reported missing and later confirmed dead.

He is buried in the Guards' Cemetary, Lesboeufs, in the Somme.