I have just found this cover which I bought for the contents.  However on the reverse there are two cachets.

On is from the 1 Bn. The Black Watch 0f Canada and seems to be typical of the many unit cachets that exist. 

However the second appears to be from the Carrier Platoon.  I have included a somewhat enhanced b & w scan of that.  From what I can find out a platoon was typically about 30 men (3 sections of 10).  This is the first time i have seen a cachet from that small a unit. 

I was wondering if anyone knows anything about this or if there are more cachets from platoon size units.  Is it genuine?

John