Well, most of western Europe stayed on CET after World War II. Initially the Nazis forced this upon The Netherlands, Belgium, Luxembourg and occupied France in May 1940, including DST. Double summer time! As The Netherlands was on Amsterdam time before the war, it went from +00:20 to 02:00 in one go. Spain followed as a gesture of political solidarity. DST remained year round until 1942.

After the war DST was abolished again, and then reintroduced in 1977 because of the energy crisis.

There has been talk about having permanent (double) summer time again, but the problem is that in winter, sunrise would be around 10 am.