Someone has already mentioned me in this thread (hey!), but I've been detained quite a few times under s.136 of the Mental Health Act, in the space of 9 months (more an 'ongoing' situation rather than lots of separate incidents).
I don't necessarily agree that I needed detaining on all of those occasions. I was putting myself in some dangerous situations though, and the police said they weren't willing to take the risk because they were concerned I was 'building myself up' to doing it (and to be fair to them, they had a point). They said they had 'genuine concerns' that I would do something I couldn't turn back from, and that they would do everything within their powers to stop me from doing that, and that they would go home happier that night knowing I was safe.
I know a lot of people have had horrible experiences with the police and mental health incidents. But I've always been very very lucky with the police where I am. The first time they got involved they took me to my flat and called the Crisis Team, but I was scared of speaking on the phone. So I whispered my answers to one of the police officers, and he sat with me and spoke aloud everything that I whispered, and he was so understanding.
The week after my mum was diagnosed with cancer a police officer sat with me on the pavement and talked to me about it, a couple of them over the times I was detained have talked to me about their own experiences with parents and cancer. I've run from the police a few times when I was scared of them, and even after that they joked with me about it and whether they could have caught up with me. They've restrained me from hurting myself and done it so gently I couldn't have had for more from them. They handcuffed me before putting me in their cars a few times and they did it gently because they 'didn't want me to hurt myself', so gently I was able to take them off.
The last time I was detained in November, they spent two hours with me trying to find a way to avoid doing it, they even took me up to the uni and asked the nursing services to keep me there overnight, although they wouldn't in the end. They've said to me more than once to give them a call if I need them and they'll come out and sit with me for a while (not convinced that's all they'd do, I think they'd certainly try to detain if that happened, and it's not something I'm ever going to do...but then I've got help since then anyway and I hope I never end up in the situation where I feel that bad again anyway). But they were great anyway, and I wish I'd be in a state of mind that I could have said thank-you to them, because I don't know that I'd be here if it wasn't for at least one of them. I don't know if it's partly because my situation was a reaction to what was happening in my life, or because I came to trust them enough to talk to a couple of them a little bit, but they really were very understanding, even when they had to do things like restrain me or check my wrists.
Apologies for the long post but a) it's on my mind a bit! and b) I really like the police (wanted to work with them before all that happened!) so I like talking about police anyway, and I can see it from their point of view too I suppose. I know when they were with me they were getting very frustrated with one of the hospitals because they weren't helpful at all, and because they were just discharging patients who, by the sounds of it, weren't really safe at all.
But yes. I have been very very lucky. But it is possible to have 'understanding' experiences with the police. And a lot of them do genuinely want to help, they just don't know how to - they get very little mental health training and the powers they have aren't always great with regards to mental health incidents.