17(1)This paragraph applies where a child is deemed by paragraph 15 to be in the care of a local authority under an order or resolution which is deemed by that paragraph to be a care order.
(2)If, immediately before the day on which Part III comes into force, the child was allowed to be under the charge and control of—
(a)a parent or guardian under section 21(2) of the [1980 c. 5.] Child Care Act 1980; or
(b)a person who, before the child was in the authority’s care, had care and control of the child by virtue of an order falling within paragraph 5,
on and after that day the provision made by and under section 23(5) shall apply as if the child had been placed with the person in question in accordance with that provision.