Especially for RupertGMT = Greenwich Mean Time
From Wikipedia, the free encyclopedia
Greenwich Mean Time (GMT) is a term originally referring to mean solar time at the Royal Observatory, Greenwich in London.
GMT DOESN'T CHANGE.In summer in the UK they put their clocks forward 1 hour - so the time there from March to October is GMT +1. This is called BST - British Summer Time. Most of the rest of Europe is GMT +1 in winter and GMT +2 in summer.
Here's a map from wikipedia to help:
blue Western European Time (GMT +0) Western European Summer Time (GMT +1)
red Central European Time (GMT +1) Central European Summer Time (GMT +2)
yellow Eastern European Time (GMT +2) Eastern European Summer Time (GMT +3)
green Moscow Time (GMT +3) Moscow Summer Time (GMT +4)