Gents, attached is a picture of my great grandfather, Leonard Berrington Atkin in his WWI uniform. Apologies for the poor quality of the shot, but I'm hoping you may have some thoughts on the significance of the devices on the cap and uniform. On the cap we can see crossed sabers with what I'm guessing is a crown up above. The insignia on the epaulettes looks to read "R.S.C.", but due to the low quality, I can't confirm this. Also, down on his left arm, you can see two crossed flags. It may be of assistance to know that he was either an Irish volunteer, or conscript (but I suspect the former). It doesn't look like any of these are rank insignia, so I'm guessing he was a very junior enlisted man.
Many thanks in advance for your thoughts!