Chucky Lucky 4, Here's one answer - Pretty much what we thought. If you want, I can send the note scan to him, or you can through his link.
- - I have not confirmed this date (04.09.1961) variety exists for the 10/- note, but I have confirmed almost 550 different varieties of notes for Tonga in The Banknote Book: http://banknotebook.contentshelf.com/pr ... 6000001EC6. I'm confident this is the most accurate, complete compilation you'll find, but there are likely many more unlisted date varieties to be discovered as Tonga changed the dates often.
If your friend will kindly share scans of his note, I'll add it to The Banknote Book.