Without a better description, I cant be sure, as I am somewhat unclear as to what is "upper right side" but it sounds as though you have a Greener type action. Google "Greener police gun" and something will come up.
The military Martini Henry safety was located beside the trigger guard. It was not used for very long as I understand.

Dumb, but learning...Prof Em, BSc(ME), CAE (FYI)