DMcG - it depends on what country the people are in, and the conventions those countries use for time. Time zones don't stick rigidly to lines of longitude, but bend around countries as they find convenient. For example, China, which because of its size and position could cover 5 time zones, actually uses only one time zone, standard for the whole country. So even far away from the equator, if you walked due north, you might find that you change time zones. As you get nearer the poles, I suppose using GMT as a standard time would become more common in unpopulated areas. Anywhere there is a real town or city, I reckon they would be covered by their country and the standard they have agreed upon.