I sent Brad as an attachment a copy of Jespersen’s Chapter 6 of his third Syntax volume of A Modern English Grammar on Historical Principles. He excerpted it pretty minimally below, and I thought the full text might be interesting to some on the list as a nuanced treatment of the pluperfect. The text follows. This is scanned OCR text that I have edited to correct OCR errors and formatted to be close to the original.
Herb
Visit ATEG's web site at http://ateg.org/