Time Difference Between London and Tokyo

Eight hours is small enough that a real overlap exists and large enough that it sits at the edge of both days. Tokyo's afternoon is London's morning. Nine in the morning in London is 5 PM in Tokyo, which gives you roughly 8 to 10 AM London time against 4 to 6 PM in Tokyo, and that band is the only one that works. Tokyo's own morning falls in the middle of London's night. Whoever books the meeting is asking the Tokyo side to stay to the end of its day, so Friday afternoons in Tokyo are a poor bet and London should resist pushing the slot later to suit itself.

Only London moves. Tokyo holds the same clock in January and July, so the difference is 9 hours while London is on standard time, drops to 8 when British Summer Time starts on the last Sunday of March, and returns to 9 on the last Sunday of October. The winter setting is the awkward one. At 9 hours, 8 AM in London is already 5 PM in Tokyo, and the usable band collapses to about an hour. London has to be at a desk by eight to catch anyone still in a Tokyo office. Teams running a standing weekly call on this route mostly accept the drift and let the Tokyo time slide by an hour rather than recutting the meeting twice a year.

The nonstop from London now runs about 14 hours, a couple of hours longer than it used to, because flights to Tokyo route south around Russian airspace instead of straight over Siberia. There is no date line on this one. What you get is a clean 8 or 9 hour advance, and eastward is the harder direction: the body is being asked to fall asleep in what it still considers the afternoon. A midday departure from Heathrow puts you into Tokyo around lunchtime the following day, which is the good version, since a full local afternoon gives you something to stay awake through and you can go to bed at a normal hour. The return home usually costs a couple of groggy mornings.