KRRC OR service dress insignia

[cbuehler]

All,
I note that the KRRC OR appears to normally have worn red backings to their cap badges and shoulder titles, but not always.
Additionally, ww1 photos show standard khaki service dress chevrons and metal trade badges instead of black on red.
Ww2 BD blouses however usually show the black on red rank and trade insignia. What about between the wars? Did they revert back to the black on red for khaki service dress or continue wearing standard khaki until ww2?
Thanks,

CB