Even though Queen Mary had the larger Guards badge she was photographed wearing what looks like a smaller version.

In 1938 for the ceremony where the Grenadier Guards were presented with new colours Queen Mary wore the smaller badge.


The badge


Queen Mary also wore this smaller badge when the Welsh Guards were presented with new colours in 1949.



Both of these occasions were after the death of Queen Alexandra and at a time when Queen Mary had her larger badge.

I suspect that she wore the smaller badge on occasions relating to individual regiments and wore the large badge only for the Trooping of the Colour which involved all the Guards regiments -- but that is just a guess.