South African.
RAILWAYS AND HARBOUR BRIGADE: An Active Citizen Force corps formed from the personnel from the two departments. In 1922 consisted of two battalions of infantry. Operated two armoured trains. In 1940 the establishment was much increased, and many of the Brigade volunteered for the South African Tank Corps. The badge is a winged wheel under a crown, with the title "Semper Paratus" below.
Page 148, The Armed Forces of South Africa, by G. Tylden.