Following on from the thread where we were talking about JKR, I've been itching for ages to talk about the ending of Troubled Blood.
We find out that the killer is a member of the caring professions and that Strike has failed to investigate this person properly because Strike had had such a good experience of this profession in the past. (For some reason I'm still trying not to completely give it away!)
It seems to me that JKR is trying to make a very obvious point: that bad people will pretend to be something they're not in order to gain access to victims and dupe the unwary. It feels like an exact analogy for the argument that sexual abusers will take advantage of self-ID to gain access to changing rooms, women's refuges, Girl Guiding etc. It also reminds me of what LangCleg used to say about not having a "sacred caste" when it comes to safeguarding: absolutely no one should be above suspicion.
And of course she's absolutely right - just look at Harold Shipman or the number of doctors and health professionals who have been found guilty of sexual abuse. Being a health professional is a very good cover for people who want to harm others.