Today I went to check microfilm records stored at Hong Kong Public Library and found following situation that are inconsistent with tz database record. * Around April 1 1941, there're no news about DST on various newspapers that I checked. Time given for sunrise/sunset around the period are also continuous (as in they're minutes within each others on those days, indicating there are no change to time standard around 1941 April 1. * I have subsequently checked Hong Kong Observatory's site and the site now list the 1941 DST start date for Hong Kong as June 15. (url is same as the one in tz file but content is different from when the 2009 comment was made) I have not tried validating the info from those newspapers as I wasn't aware of the table's current content until I stopped using the library. * And then, on September 30 1941, according to Ta Kung Pao (Hong Kong edition), it was stated that fallback would occur on the next day (the 1st)'s "03:00 am (Hong Kong Time 04:00 am)" and the clock will fall back for a half hour. (03:00 probably refer to the time commonly used in mainland China at the time given the paper's background), after it was spring forward for an hour months ago. I cannot find out record of English newspaper from that day, but the sunrise/sunset time given by South China Morning Post for October 1st was indeed moved by half an hour compares to before. * After that, in December, the battle to capture Hong Kong started and the library doesn't seems to have any record stored about press during that period of time. Some media resumed publication soon after that within the same month, but there were not much information about time there. Later they started including a radio program guide when they restored radio service, explicitly mentioning it use Tokyo standard time, and later added a note saying it's half an hour ahead of the old Hong Kong standard time, and it also seems to indicate that Hong Kong was not using GMT+8 when it was captured by Japan. * Image of related sections on newspaper: 1941 September 30, Ta Kung Pao (Hing Kong) , "Winter Time starr tomorrow": https://i.imgur.com/6waY51Z.jpg (Chinese) 1941 September 29, South China Morning Post, Information on sunrise/sunset time and other things for September 30 and October 1: https://i.imgur.com/kCiUR78.jpg 1942 February 5, The Hong Kong News, Radio Program Guide: https://i.imgur.com/eVvDMzS.jpg