Many thanks for all those observations. The most likely culprit is:
Little.auk wrote: ↑20 Apr 2023 09:46
..... will gradually drift away from "real" time, until it goes outside the allowed tolerance.
In consequence in windows settings I set the time automatically ON
and Synchronised my clock.
Then set the time automatically OFF and adjusted the time manually.
So far this seems to be working.
Why do I want to do this? Very similar to:
jbtapscott wrote: ↑20 Apr 2023 11:12
.... I have also found issues with Ms Outlook (the desktop version rather than cloud), in that auto changing of time zones and / or clocks caused problems on certain calendar events
I found that if I made entries in Outlook calendar in a different time zone say in the USA, when I got back to the UK, it showed as 5 hours out (understandably in an international business sense) and sometimes a different day! In consequence I no longer use the "time" in outlook and just prefix my "subject" with the time instead.
There might be a way to override this "feature", but I am happy with my simple fix for personal use.