All this debate about time reminds of an amusing incident in my early days of flying long haul when we flying from Karachi to Calcutta. Of course in those days we didn't have the all singing/dancing clocks of today's jet age which automatically synchonise to UTC via GPS but steam driven clocks which had to be wound and set correctly.
We often listened in to the BBC World Service to get the pips and synchronise the clocks and, of course, listen to the news. I had just done a time check on the pips and called ATC to give a position report. The controller said "Airways time is XXXX, confirm time over AAA was YYYY?" The "Airways Time" was about 5 minutes wrong! When we advised the controller that we had just checked our clocks against the pips, he still insisted his time check was right and we were wrong! Happy Days