I'm all for nuance in historical portrayals, and for showing that even Fascists can have sympathetic, vulnerable and troubled elements. But this series goes to far! Or rather, it's fine to show Unity and Diana as strong, attractive women, but not to give the impression that they just happened to chose the wrong side, or had a bit of blind spot when it came to Hitler. I feel there must have been a deep darkness in their characters, which doesn't come across. Nor does the true evil of the ideology they are embracing. Yes, it does show the Battle of Cable Street, but there's an impression that this was the "lower classes" getting a bit out of hand, rather than the much deeper danger that so many in the ruling classes found fascism congenial, if it had just been a bit more polite. Speaking of which, the Mitford father, mother and brother are shown in a very misleading light. Farve was, according to Jessica, "one of nature's Fascists", and his objections to Unity's association with Hitler were based on his hatred of Germans rather than any disagreement with Hitler. He and Muv went to the 1937 and 1938 Nuremburg rallies and were "charmed" by Hitler when they met him. And the lovely Tom was, according to Wikipedia "a Nazi sympathiser, who [in WW2] was send to the Pacific after saying he did not want to fight against Germany".
On the plus side, the series is superbly acted and filmed, and cracks along at an entertaining pace. But should Nazi sympathisers be portrayed primarily as entertainment?