rdperrin - I'm sorry, when I first got all interested in italy and its history, I read books about it almost like a bath of books.. and after I centered interest on piazzas, I read more and more, into the hundreds.
As a guess, perhaps the mention was in Luigi Barzini's The Italians, or Branko Bokun's Spy in the Vatican... but maybe neither of those. Perhaps a book by Bernard Berenson.. which I can't even remember the name of, and is least likely of the three - though I almost remember he was the source for information about jews being shot in the campo in Siena. Don't trust me, this is all floating memory. I still have the books but they're in boxes, so I can't easily find the books much less the writing about Pitigliano. I'll post back here if I ever build some bookshelves and empty those boxes.
I did look up Bokun, perhaps a year or two ago, and apparently he lives in england and is still writing (he would be well advancing in age by now..)
Perhaps you could find him online and send him a question. (He was head of the International Red Cross in Yugoslavia in the years of WWII.)