The son of Ernest Alfred Thompson, Aubrey Denzil Forsyth-Thompson was born in Natal and grew up on a farm in the Mooi Riverarea.
[1] He was educated at Weenan County College in Mooi River, which his parents founded and where they taught.
[1][2] In 1917, he went to England to join the British Army, and was commissioned a second lieutenant in the Royal Field Artillery, seeing combat in France.
[1][3] In 1919, he left the Army and went to New College, Oxford, to study for a shortened degree in Modern History, graduating BA in 1920.
Forsyth-Thompson married Kathleen Esther Murray in 1942; they had three children, all born in Uganda.