There has been a slew of historical 'speculative' fiction (my term for such books) such as The Chaperone, Mrs Lincoln's Dressmaker, Hemingway's Girl and now Freud's Mistress.
I just find it very convenient that the story writes itself out while the author speculates and fill in the gaps since they are invariably based primarily on actual people/characters/situation but that little gap for imagination. And it does come across as being lazy as well.
One (the author/s) knows the beginning, the middle and the ending so let's just weave in bits and pieces over the parts that no one will really know.
Feels like a cop out to me and however artful the writer/writers might be, it just feels formulaic, without the rigours of historical non-fiction or the imagination of quality historical fiction either.