Of course the similarities between the letters to the UN from Schiel & Denver and T&C suggest shared authorship (Reid-Kapo), but there are also some clues in the T&C book (text http://pastebin.com/2GpQARh5) that suggest it was written by someone British, not American. Such as:
singleton life—not single life
gammon—here we would say maybe smoked ham? I had to look it up
“rehearsal dinner”, this being a Pembroke tradition — note the quotes (this was the first thing that jumped out at me and it made me go back and read more carefully). I think rehearsal dinners are a common thing in weddings
hired clothes / hire car — instead of rented / rental
fulfil — instead of fulfill
pick nick — instead of picnic. Never ever seen that before
Maybe more that I missed. The text as a whole is a bit clumsy and probably few people apart from the author have stayed read the entire thing. It’s strange the amount of detail in certain parts, like the Gen Con bit.
Idk, i find this whole thing fascinating.