Officer gilded sleeve eagles

[Terra Nova]

These are left and right facing eagles of very high relief. They were acquired together and both appear to have been manufactured at the same time, with identical fittings and finishes. The only discernible difference (aside from left- and right- facing) is that the viewer's left facing eagle's tail has a slightly more defined "notch" in the middle bottom of the tail feathers.

Looking at previous posts, I'm thinking that they are fairly early issue insignia that were worn above the officer insignia on the lower portion of the sleeve.

Would someone kindly confirm:
1. the probable period of use/manufacture; and
2. if my conclusion that they are, in fact, early RAF sleeve eagles, is correct

Thank you.

with kindest regards to all,

Tim