Here's a link on the R22eR of Canada. This great regiment has a lot of history behind it! Perhaps you might find your question in the links on this web page?
The R22eR is allied with the Royal Welsh Regiment, so perhaps this is a trans-Atlantic tradition or gift from them, and pass down throughout the years? The other answer could be, it as gift to the regiment from H.M. The Queen. Again, I don't know for certain, just vaguely remember reading something on this subject, a number of years ago!?