‘‘It is important to remember (1) that the roles of the court and the expert are distinct; and (2) it is the court that is in the position to weigh up the expert evidence against its findings on the other evidence. The judge must always remember that he or she is the person who makes the final decision.' ‘In a case where the medical evidence is to the effect that the likely cause is non-accidental and thus human agency, a court can reach a finding on the totality of the evidence either (a) that on the balance of probability an injury has a natural cause, or is not a non-accidental injury; or (b) that a local authority has not established the existence of the threshold to the civil standard of proof …’