When you look at the design, it seems to me that the proper use of the piece would have been rotated 90 degrees to the right, relative to the first picture. The design you have is very popular it seems as there are hundreds of variants out there. But take these two for example:
The slots appear to go different directions.
Any way, can't say thank you enough for this thread. Apparently I found a different type of concho once while detecting and always thought it was part of a coat button or something. When I searched "concho" on Google, I found all sorts of them with the same design as the thing I found:
Never even thought to post it here before because I found it in a flower bed and thought it had simply fallen off someone's coat in recent history. This makes it a little more interesting.