According to all of my extensive reference material on RA insignia there is no version of the standard RA forage cap badge that had any kind of addition to its front that would cause the strange silhouette that we see in the subject photo, which seems exacerbated in the close-up. The strengthening piece that Max mentions was at the rear and unseen from the front. The only ever addition to the front of the badge was a small ‘M’ in white metal at the bottom centre that was for Militia units of the RA and similarly fitted to badges of the RE. It seems then that from a process of elimination what we can see is either, a horseshoe shape good luck token that the sitter attached to the badge as a jape, or a distortion caused by an optical illusion, perhaps a reflection, as part of the photographic process. Were I a gambler my bet would be on the latter and the more I look at the main photo rather than the close-up, the more I see the natural aspects of light and shade caused by reflected light on the highly polished badge.
