I've just posted the reply below to Je Kan. Would also value your thoughts on the ethical question and would be happy to post a slightly revised version soon if you feel that would be recessary.
Many thanks for your comments. Am now going thru the paper and checking. Also thinking of adding a few words to help clarify some areas and improve overall flow, which may involve incuding one or two more subheadings to help the reader.
Just an ethical question I've been mulling over for a few days. I have felt comfortable with the idea that as the letters I have included are from my own hand and do not mention other persons by name (i.e. they can't be identified), there would be no ethical issues. In other words, I have not sought 'permission to publish' from those to whom I have sent the letters reproduced in the paper. Your views?
In any case, would you like me to send you the revised paper (DRAFT 6)?