Jess raised the point of police accessing private places, to bring people to a place of safety for assessment.
In theory, this is covered under section 135 of the Mental Health Act 1983.
Someone's in a private place, refuses help, seems to need care, generates significant and risky problems (for themselves or others), what's to be done? An Approved Mental Health Professional presents their concerns to a magistrate who can then issue a warrant for police to access the person, eg forcing their way into their home, to then take them to a place of safety.
Unusually, they're then locked up in a place of safety for 72 hours, but I can't discharge them from the section 135. The police or the Approved Mental Health Professional does that.
In practice, it's hardly ever used. I've seen it used once.
If someone's in their own home or garden or other not-public area, invariably a section 2 is considered instead.
Jess is quite correct that this means someone who's presenting with a health problem, and consequent behavioural changes and evidence of ill health being manifest to one and all, then has an ambulance crew arrive who do . . . what? If detained under the MHA 1983 then they can be conveyed to hospital. If they're evidenced to be incapacitated adults (with respect to this decision) then they can be conveyed to hospital (if it's in their best interests) under the MCA 2005. Our ambulance crews need to be given completed locally agreed forms documenting this lack of capacity before they'll convey.
So locally, the use of the MHA 1983 (with sections 2 and 136) and MCA 2005 (sections 4 and 5) sort most out of hours problems where statutory powers need to be used to orchestrate care. Rarely, very rarely, section 135 is considered.