“In the second category, there will be cases where on the evidence it is possible for the local authority to satisfy the threshold criteria. In those circumstances, an application to withdraw the proceedings must be determined by considering (1) whether withdrawal of the care proceedings will promote or conflict with the welfare of the child concerned, and (2) the overriding objective under the Family Procedure Rules. The relevant factors will include those identified by McFarlane J in Oxfordshire County Council v DP which, having regard to the paramountcy of the child's welfare and the overriding objective in the FPR, can be restated in these terms: the necessity of the investigation and the relevance of the potential result to the future care plans for the child; the obligation to deal with cases justly; whether the hearing would be proportionate to the nature, importance and complexity of the issues; the prospects of a fair trial of the issues and the impact of any fact-finding process on other parties; the time the investigation would take and the likely cost to public funds.”