" When ... a court holds that the defendant was under a duty of care, the court is stating as a conclusion of law what is really a conclusion of policy as to responsibility for conduct involving unreasonable risk ..."
" ... there is always a large element of judicial policy and social expediency involved in the determination of the duty problem ..."
it would be worth students considering it in the light of the Supreme Court's decision in Michael v Chief Constable of South Wales  UKSC 2 in which the court maintained the position established in Hill v Chief Constable of West Yorkshire  AC 53 and did not impose a duty of care on the Police for their handling of a 999 call from Joanna Michael.
See also, Caparo Industries plc v Dickman  2 AC 605 where Lord Bridge stated:
"What emerges is that, in addition to the foreseeability of damage, necessary ingredients in any situation giving rise to a duty of care are that there should exist between the party owing the duty and the party to whom it is owed a relationship characterised by the law as one of "proximity" or "neighbourhood" and that the situation should be one in which the court considers it fair, just and reasonable that the law should impose a duty of a given scope upon the one party for the benefit of the other. But it is implicit in the passages referred to that the concepts of proximity and fairness embodied in these additional ingredients are not susceptible of any such precise definition as would be necessary to give them utility as practical tests, but amount in effect to little more than convenient labels to attach to the features of different specific situations which, on a detailed examination of all the circumstances, the law recognises pragmatically as giving rise to a duty of care of a given scope. Whilst recognising, of course, the importance of the underlying general principles common to the whole field of negligence, I think the law has now moved in the direction of attaching greater significance to the more traditional categorisation of distinct and recognisable situations as guides to the existence, the scope and the limits of the varied duties of care which the law imposes."
In an article "Viewpoint: Supreme Court preserves police immunity from negligence liability", the author, by Dr John Fanning - Law Lecturer University of Liverpool - comments:
"Court-watchers may feel that Michael’s case bucks a recent trend. During the last decade, the Court has restricted the scope of the armed forces’ “combat immunity” (Smith v MOD) and abolished the immunity of expert witnesses (Jones v Kaney) and barristers (Hall v Simons) from negligence claims. The Court’s reasoning in those cases may have raised doubts about the future of similar immunities enjoyed by the likes of the police and fire brigade. Michael’s case dispels any hopes of new trend in the Court’s decision-making."
See also the useful overview at Bits of Law