In case it can be of help - According to
this site:
"
This was not the first experiment to shift the clocks in winter. In the Second World War (1939-45), Britain had adopted Double British Summer Time, with the clocks one hour ahead of Greenwich in winter and two hours ahead in summer."
And in Germany from
here : "
After the end of the war and the proclamation of the Weimar Republic in November 1918, summer time ceased to be observed in peace time. Summer time was reintroduced in 1940, during World War II, in an attempt to save energy for the war economy."
Not much impact on December events though.....
Br
Göran