[Bill A]

This thread hasn't attracted much more attention, so I will add my conclusion. Luke, thanks. You were bang on on the age, and on top of that you provided a very good explanation as to the variation, of which I had been unaware.
The badge on the left came from the estate of a soldier from the 87th Bn, Canadian Grenadier Guards, and he was killed in action. The badges had not been messed with (any added) over the time between them being sent to the next of kin and my acquiring them. It is definitely a WW1 badge. The other is a very common CGG badge, often listed on ebay or seen at shows. Inexpensive and easily found. This can't be said for the example on the left.
Again, thanks for the primer on the cyphers Luke.