Yeah, when BC is in his Holmes costume, they could be brothers! But otherwise, perhaps not? He looks so different out of costume.

I loved this version of Holmes, and I love the movie Atonement, and when my sister pointed out that "he who plays Holmes is that creep from Atonement!", well that was a big CAN'T UNSEE moment for me... I had not even realized that they were played by the same person!