Can I just say, that I like and respect Sally Donovan. She’s a cop. She weighed up the evidence as she saw it and came to a not unreasonable conclusion. And- as unpopular as this opinion might be- I can easily see why she would distrust and dislike Sherlock. Don’t forget, she’s a black woman in a profession still dominated by white men. She’s probably worked all her life to get away from people like him.