Chris:
The Kynoch box-colours were red-and-yellow for nitro cartridges, red-and-blue for 'nitro-for-black' cartridges, and red-and-green (as pictured) for black powder Express cartridges.

Note that Kynoch red-and-green BP boxes are uncommon because the BP era had essentially finished before the amalgamation under the Kynoch name. Most Kynoch packets encountered today are post-WWII red-and-yellow boxes for nitro-express ammo.