"In effect a last resort"
It is interesting to note in Peter Jackson's judgment here
(2) In this Court there is no disagreement in relation to legal matters. With the advantage of the decision of the Supreme Court published only yesterday in the matter of Re B (A child)  UKSC 33 it is clearly understood that an order of the kind that was made in this case can only be made where it is necessary and proportionate and in effect as a last resort in meeting the needs of the child concerned. Further, when considering arguments about the manner in which the trial judge approached matters, the question that the appeal court must ask itself is whether the judge was wrong.
What is interesting about the Supreme Court decision is that it lowers the threshold for challenging adoptions through appeal from "plainly wrong" to "wrong". Although anyone who has studied any substantial number of care proceedings knows that adoption is not "a last resort", but the preferred option for local authorities for children who are of an age that can result in an adoption. I have the 2012 figures (that is to 31st March 2012) for Infants (children under 5).
Of the 5,800 children who left care 2,300 were adopted, 500 were subject to a residency order and 870 a special guardianship order. Only 1,100 returned home. 380 left care for "another reason". (10 died and 60 transferred to another LA).
What do we learn from this. We learn that less than a fifth of children that leave care under 5 go home. It is important to note that an interim care order is granted only on "reasonable grounds" not actually proof. Care is defined on the narrow ground of children compulsorily in care rather than including children on S20.