The General Medical Council has issued guidance which permits disclosure of confidential information even in the absence of a patient's consent when it is, in the view of the doctor: 

necessary to protect the child or young person, or someone else, from risk of death or serious harm. Such cases may arise, for example, if

a) a child or young person is at risk of neglect or sexual, physical or emotional abuse

But this falls far short of requiring a breach of confidence in every case. The doctor has to balance the public interest in disclosing confidential information against the patient's and society's interest in keeping medical information confidential:

A disclosure is in the public interest if the benefits which are likely to arise from the release of information outweigh both the child or young person's interest in keeping the information confidential and society's interest in maintaining trust between doctors and patients. You must make this judgment case by case, by weighing up the various interests involved.

In some cases doctors will agonise before deciding that the involvement of the police is likely to harm rather than assist their patient. The last thing that will help satisfactorily to resolve the sort of dilemmas that arise is the requirement to summon PC Plod to the waiting room or, even worse, the fear that he will turn up without an appointment, with an arrest warrant to elbow his way past the receptionist.

And from the teenager's point of view, knowledge of a doctor's legal duty to report would make her less likely to reveal what is going on. The same principle applies to other professions with a duty of care. What child would not dread the prospect of revealing to another teacher that dear old Mr Chips, far from being a respectable pillar of the school community, is in fact a dirty old man? If they know that the police will inevitably be informed, that dread could become so great that it is easier to say nothing at all.

As well as deterring genuine complaints, a legal obligation to inform the authorities about suspected abuse would also encourage spurious ones. Teachers in particular are already peculiarly vulnerable to malicious complaints but at least they have the reassurance of knowing that if a school decides that a complaint is utterly ridiculous it need not be reported to the police. Mr Starmer's law would, in effect, make it compulsory to report any complaint, however absurd it might be, because a headteacher or governor who failed to do so would run the risk of prosecution. The law might require "reasonable belief" rather than mere suspicion, but what headteacher would have the courage not to report every rumour and snippet of gossip, which the police will then have to investigate?

Even if sensitively done, such investigations waste valuable police resources and cause acute embarrassment, alarm and humiliation to the innocent. It is not exaggerating to say that they can destroy lives and tear families apart. Even if the publicity consequent upon such investigations does not lead to the lynching of an innocent man on the basis of a groundless rumour — as occurred in Bristol in July when Bijan Ebrahami was beaten and burned by vigilantes because they thought he was a paedophile — these are not trivial concerns. Were there solid evidence that children would benefit from the implementation of Mr Starmer's proposals then they would deserve support. In its absence we should be deeply sceptical of introducing a law that would deter frightened children from seeking help, criminalise dedicated professionals and lead to the police investigating and shattering the lives of innocent people.