Looking at the time zone map on Wikipedia we can see that countries such as France and Spain technically should have a time zone of UTC+0. Wikipedia says:
France previously used GMT, but was switched to CET (Central European Time) during the German occupation of the country during World War II and did not switch back after the war.[15] Similarly, prior to World War II, the Netherlands observed "Amsterdam Time", which was twenty minutes ahead of Greenwich Mean Time. They were obliged to follow German time during the war, and kept it thereafter
But Spain was not occupied by Germany… How did it happen that their time zone is UTC+1 then?