The Spanish Flu epidemic followed quite shortly after the end of WWI - it's believed it's spread was increased by the troops coming home form the front lines. However Edward VII died in 1910 and WWI was a huge watershed in British politics and society so the period after that isn't characterised as Edwardian by historians at all. So even if we give them the idea that the aftermath of WWI and the Spanish Flu caused a lot of simultaneous misery, what the soldiers came home to was very pretty far from being 'Edwardian Britain'.
In fiction of course everything is possible - maybe in their version Edward didn't die as early and reigned through the war. But in terms of the real world it's rather sloppy wording, yes.