Guards M15 markings

[chinstrap]

I've been looking at an M15 with a very well fitting and well aged Guards plate but with extra holes and the markings 178R and ER1. My inexpert interpretation is that the haube would have originally had a Saxon plate as I believe the 178th was 13th Royal Saxon, but it was then re-issued to Eisenbahn Regiment 1, which I believe was attached to the Guards. and hence the Guards plate would be correct. Have I got this right ,or am I completely on the wrong track (so to speak!).
Patrick

 

[poniatowski]

Photos would be good, but just without seeing anything my inexpert advice would be:

If the extra holes are plugged and the new ones "grommeted", then I'd say you're probably on the right track. If not, I'd be suspicious of the helmet.

Ron