The illustrations ARE pre-WWII indeed, but the paradigm of classical male dress is still valid: the suit, the blazer, the trousers, the tie... If I had time to search, I'm sure I could come up with a couple of 21st century pictures with exactly the same situations as above - but they would not be very easy to find...

You don't have to ask anyone permission to be yourself. If you like DB, you can wear it any way you please and NOT look like you're coming from a funeral. You can wear it with aplomb in your leisure time, day and night, in and out. Your dark blue blazer can you take you many places, depending on what you pair it with (and it's informal anyway, by nature).
It's no trouble driving in a DB coat, either, I assure you - none at all. They're great in summer, too - when and where it's not very hot, of course (but SB coats can be just as unbearable in certain climates).
Everyone is a minority in some respect or another. How everybody else dresses is their business, isn't it? So don't be judgmental, but don't let others dissuade you from dressing as you please, either.
Long live the DB coat!
