I think the printlocaltime(&timeinfo) returns a boolean as to whether the time is plausible / has ever been set, rather than my assumption of an immediately preceeding successful NTP set. My plan is to clear the &timeinfo struct before going to sleep so then a getlocaltime(&timeinfo) test on awakening is a true test of whether the RTC clock has actually been synchronised. That would make the code and explanation much clearer. I'm not yet sure how to render &timeinfo implausible. It is still to test...
12TA