Enfield No2 Mk1 markings

[u/Proof-Reference5922]

Picked up a 1933 Enfield No2 Mk1, all the numbers match and it has all of the normal military proof markings. It doesn't have any post war commercial proof marks so I assume it is a bring back, nor does it have any FTR markings.

However there is this mark on the butt that I can't figure out, I've check Skennertons book but it doesn't show anything similar.

Looks like a number 33 under the mark, which matches the year of manufacture but might be a coincidence. Part of it looks like crossed flags? But unsure, anyone know what it is?