you can go on to :-
Go to the police RULES in custody: PACE
know about the guidelines to prosecution, when to prosecute - and when not - divert instead
The APPROPRIATE ADULT means, in the case of a: (a) juvenile: (i) the parent, guardian or, if the juvenile is in local authority or voluntary organisation care, or is otherwise being looked after under the Children Act 1989, a person representing that authority or organisation'Mentally vulnerable' applies to any detainee who, because of their mental state or capacity, may not understand the significance of what is said, of questions or of their replies. 'Mental disorder' is defined in the Mental Health Act 1983, section 1(2) as 'mental illness, arrested or incomplete development of mind, psychopathic disorder and any other disorder or disability of mind'.
When the custody officer has any doubt about the mental state or capacity of a detainee, that detainee should be treated as mentally vulnerable and an appropriate adult called.
3.16 It is imperative a mentally disordered or otherwise mentally vulnerable person, detained under the Mental Health Act 1983, section 136, be assessed as soon as possible.
If that assessment is to take place at the police station, an approved social worker and a registered medical practitioner shall be called to the station as soon as possible in order to interview and examine the detainee.
Once the detainee has been interviewed, examined and suitable arrangements made for their treatment or care, they can no longer be detained under section 136. A detainee must be immediately discharged from detention under section 136 if a registered medical practitioner, having examined them, concludes they are not mentally disordered within the meaning of the Act.