Our system uses the standard IANA Timezone database. The display on our website’s time zone drop-down only shows the primary offset for UTC for a city (as not every region shifts daylight savings at the same time). Which for Europe/London is UTC+0, for example. This means that when you select Europe/London in the UI (user interface) the DST (Daylight Saving Time) rules are respected and the time will include the +1 offset correctly throughout the system regardless. We just currently can’t easily display the current effective offset in that dropdown at this point.