"The Butler Did It"

I took this image from the TV Tropes entry about this alleged cliché of old mystery fiction, more precisely whodunits. I sai alleged as, although it is a common trope, it has barely been used during the Golden Age of crime fiction, as this article from the Guardian explains. The butler, may not, but from when I used to read whodunits, I remember quite a few servants culpable of some crime or other, albeit rarely THE murderer/big baddie. The villainous butler or servant must be ingrained in our psyche, as I remember as a child imagining all sorts of scenarios for our make belief whodunits games (yes, we used to play these) when the staff of a household was indeed the assassin. I guess nobody would ever suspect the faithful butlerof any sinister dispositions...