Don't know but there is one on-line with a red strip:
https://www.militariazone.com/cloth-...4#.YvDyu6DMI1I
Could they be a "company" indicator?
A (EXETER & EAST DEVON) COMPANY, DEVON ACF
B (PLYMOUTH & DISTRICT) COMPANY, DEVON ACF
C (NORTH DEVON) COMPANY, DEVON ACF
D (SOUTH DEVON) COMPANY, DEVON ACF
.