GRV 'locket'

[GTB]

I wonder if anyone has come across or seen a similar item to this apparent 'locket'. It is a brass decorative circle, ensigned with a KC, having G and R to left and right, and GEORGE V at bottom. Some enterprising person has inserted a GRV postage stamp inside the voided 'window. I am curious to know what it would have originally looked like (probably a photo of the King?). Size as for a normal cap badge
GTB