Analytics has two GMT time zone options.
What is the difference between these two time zones?
Greenwich Mean Time; Monrovia, Casablanca GMT - This time zone setting will correspond to the GMT time zone (UTC time) throughout the year. Irrespective of the time of year, it will reflect the UTC time zone with no adjustments for Daylight Savings Time
Greenwich, Dublin, Edinburgh, London, Lisbon - This time zone setting will correspond to GMT+1 (BST time zone) during summer and will fall back to the GMT time otherwise.