I just found a lovely article and interview with Romola, Bill Nighy and Stephen Poliakoff. The article is very long so here is one of her answers. A link to the rest of the article can be found below.

CS: I’m interested in the cast’s connections to this time. Bill, you probably have parents that went through this, but Romola, when you read the script or learned about it, what kind of resonance did you have with it? Was this an interesting subject for you?
Romola Garai: Yeah, I mean, for me very much so. My father’s family are Hungarian Jews who emigrated first to New York and then to the U.K. So similarly to see them is obviously a very personal investment in the fact that Britain has taken on the mantle of the great protector, especially with regard to the Holocaust. Obviously it wasn’t ever as simple as that, specifically to do with the policy of appeasement. I was thinking what was really apparent in the script to me in terms of what Stephen is saying is being a thriller, but a psychological thriller, not something that’s just a plot, you know, it’s very much based in psychological fear like all of Hitchcock’s great films. The fundamental fear of Anne is that your family doesn’t really love you. That’s the kind of great Freudian fear at the center of it and that was something I think children who are adopted specifically fear. I don’t think that that’s such a psychological, a deep-rooted psychological fear that people have rarely addressed in film before.

CS: How about playing an actress from the ’30′s? Did you do some research in the differences in behavior or was that all in the script?
Garai: Yeah, obviously the films of Hitchcock were very important as a kind of reference point in terms of the material. They were also important to me because that were the kind of films that Anne had placed more cards in. So, it was useful, you know, not only to getting a sense of the kind of film that Stephen was making, but also in terms of character research.

Source: ComingSoon.net