The problem you encounter casting Stanley Tucci in literally any role is that he’s too preternaturally charming. You have to work against the unstoppable force of nature that he represents for us to do anything but love him. The Children Act unfortunately, is nothing but blandly directed and has to struggle against Ian McEwan’s second script this year imperfectly adapted from his own novel.
There’s this dichotomy to Stanley Tucci’s filmmaking. People cast him because he can be the most charming person alive. Like, all he has to do is appear on screen and I’ll be totally on board with whatever he’s doing. Even when Peter Jackson is being the most manipulative and overt a filmmaker has ever gotten in casting the man as a paedophile: gives him that combover, the creepy moustache, it all chafes against the fact that, well, it’s Stanley Tucci. It’s a fine performance, I’m not blaming him for that flick.