Archibald Matheson Mccallum was born on 30 August 1896 to Archibald Mccallum and Elizabeth Matheson. Archibald Sr was schoolmaster at Balallan, but moved away from Lewis in 1898. Archibald Jr joined the Australian Imperial Forces in 1915, and served in France until 1917, when he was discharged due to severe thyroid problems. Archibald Jr returned to Australia, where he lived until his death in 1959 (or thereabouts).
Archibald Sr is quoted as having two children (DJ and Christina), but it would appear that Archibald Jr is in fact a third child.