That of course is if you consider the floor of a side chancel walkway a conspicuous spot.
How appropriate for the failed med school drop-out and the equally unaccomplished theologian, Darwin. I make it a formal practice to wipe my feet on Darwin's grave marker on every one of the many occasions I have had the privilege to visit the Abbey. Each of my children in fact have had the same pleasure as well.
Thankfully, Sir Isaac Newton, a real scientist, is buried and memorialized in an exquisite and conspicuously visible place in full view as one faces the altar on the left.
And, for the record, there are many nooks and crannies in Westminster as you well know, and to deny that Darwin is buried in a prominent place is really denying reality, whatever your views on evolution, God and creation.