FIRST S.A.E.C. REGT. (First South African Engineer Corps Regiment) Cloth shoulder title

FIRST S.A.E.C. REGT.” stands for First South African Engineer Corps Regiment. 
Construction:
The red wool background with dark navy/blue chain-stitched lettering is entirely typical of South African formation titles of the WWII period. 
The South African Engineer Corps served in East Africa, North Africa (Western Desert), and Italy during WWII. The “First” designation distinguishes it from later-raised engineer units within the Union Defence Forces.