Born 1879, only son of Lieutenant-Colonel Edward 'Loopy' Straitt-Jackett and the Hon. Felicia Straitt-Jackett (nee Warming-Knightley). Educated at Mr. Thrashem's Academy for Young Gentlemen. Joined Army 1897. Served in Sudan, Gold Coast, Basutoland, Matabeleland.
Despite never hearing a shot fired in anger Major Straitt-Jackett served with distinction during World War 1, commanding 13th (Colonial) Field Kitchen Unit stationed in Bulawayo. He was present at the Tsetse Valley Incident when a crowd of rioting Native miners were subdued by volleys of plum duff hurled by his cooks, for which action he was awarded The Order of the Yellow Buffalo (2nd Class).
A good friend of the renowned Major Denis Bloodknock, Major Straitt-Jackett joined the B.U.F. in 1935, in the mistaken belief it was a book club.