For those of you interested in the theoretical ground of this discussion, I can offer only this meager fare.
Most modern theories of tense and aspect developed in response to a very small section in Hans Reichenbach's "Elements of Symbolic Logic" (1947). Reichenbach there considers, in general terms, the difference among these three sentences:
I have lost my keys.
I lost my keys.
I had lost my keys.
Each sentence describes the same PAST event. ...