You can see how Kate Beckinsale saves J. Sturgess' scenes sometimes.
Sometimes the male lead's (Dr. Newgate) acting is weak in some scenes.
He simply doesn't look either on the same quality lever either he does his parts over the top or over sentimental. Sometimes his acting seems somewhat unconvincing.
Then, when camera switches to Eliza, if they share a scene, she shores his dialogue up as legitimate and credible - as "I saved your (acting) ass right now, didn't I ...".
In the last third of the film she did it more than a few times.
Ben Kingsley and Michael Caine are two classes above everyone else. Then Kate Beckinsale follows.
Sturgess' parts are the weakest IMHO.
I think she'd never be with him as a woman IRL, although she does her best, as Eliza Graves, to show affection and attraction towards him.
So the "chemistry" between their characters works, but its obvious that their acting is like "teflon" shield - almost impossible to penetrate and to see their real side. Almost ...
So I'd bet my money on Kingsley (or Caine) to have much more chance at winning her heart IRL than Sturgess.