As to how this would arise, potentially, in the department store context, perhaps a person is observed by security officers—whether by a closed-circuit television or face to face—while stealing merchandise. They would see the person leave the store and would effect the arrest at that time. They could detain the person, but there's an obligation for them to turn the person over to police as soon as possible.
What we have been advised happens in the ordinary course of events is that they would then contact the police by telephone, indicating that they have a person in custody, so to speak. Sometimes, if it's a less serious offence, the police give them a number over the phone. They get the person's details, their contact information and so on, and then they release that person immediately. The person would then receive at home a notice to appear or a summons to appear in court.
So it wouldn't be a situation where the thief would be locked up in jail or detained for a prolonged period of time. Otherwise, the police would attend, and the police would take over at that point in time and would remove the person if the person were disruptive in any way or potentially causing threats to other people in the vicinity.
Is that getting at the heart of your question?