Well, that is partially correct. London time is GMT, but not just now because Londen (as most —if not all— of Western Europe) is in Daylight Saving Time. The second DST ends for England, adding an hour to the current time would give wrong results if what you want is "London time." DateTime knows about DST details — which varies between one country and another! Although the EU is, as I recall, pretty consistent about it — so you really should look into it.