On Wed, 3 Mar 2021 at 11:10, Michael H Deckers <michael.h.deckers@googlemail.com> wrote:

While you are at it, let me quote

        [Ian R Bartky: "One Time Fits All: The Campaigns for Global
Uniformity".
        Stanford University Press. 2007. p 24..26]:

            3. On 10 September 1945 Tonga adopted a standard time 12 hours,
            20 minutes in advance of Greenwich. On 19 October 1960 the
            legislation was amended by shifting to a time 13 hours in
            advance, and continuing the Eastern reckoning of the days.
            Tonga's daylight saving time, observed in 1999 and 2000,
            was abandoned by 2002. I thank Rhys Richards for these dates.

I wasn't finding this quote on the pages specified in the previews on Google Books, so I borrowed the hardcover copy from my institution's library. Perhaps it amounts to a difference in editions, but I see this text as part of endnote 3 in the "Epilogue" section, on page 255, which seems to be more inline with the Google version, too.

The second sentence of this quotation further supports what the Air Almanac points to regarding a 1961 change. In the main text that the endnote supports, as part of a discussion about the (apparently unintentional) race "to be the first in the world to see the dawn of the new millennium", Bartky says that "since 1961 [Tonga's] official time has been thirteen hours in advance of Greenwich time" (p. 202) which further supports our suspicion that the effective date of the transition was 1961-01-01.

Since this helps us to better sum up what we know, I've installed the attached patch to commentary.

--
Tim Parenti