But Mr Starmer's proposed law is not so wide-ranging. It would not apply, for example, to a future Gerry Adams. He suggests that the legal obligation to report sexual abuse should apply only to "those in a position of authority" over children. While it may be a little unclear whom he had in mind, it was certainly not those such as Mr Adams, who exercise authority deriving from a position as a gangster capo di tutti capi. He was referring to those whose professional duty it is to exercise some form of care for children, in particular doctors and teachers.

All these professions now issue guidance on how their members should handle allegations of child abuse. There are any number of protocols, directives and procedures to ensure that suspicions are investigated. Any parent taking a child to hospital with a broken bone or bruising will be familiar with the polite but suspicious questions that are almost always asked in such circumstances. If a doctor or teacher is made aware of an allegation of sexual abuse it is overwhelmingly likely that he or she will inform the police. A failure to comply with professional guidelines is likely to be a serious disciplinary matter.

But such professional guidance does not have the force of the criminal law, and this is what Mr Starmer wishes to change. Wherever there is "reasonable belief" that abuse has occurred he wants the police to be informed; and, upon the completion of their inquiries, he wants the CPS to decide whether a prosecution should take place.

Mr Starmer offered no evidence that a reluctance to involve the police or the CPS is seriously contributing to child abuse or preventing its investigation. Before creating a whole category of new offences the most crucial question should be what impact the adoption of Mr Starmer's proposal would have on abused children.

In some cases the first person to learn that a child has been sexually abused is a doctor, perhaps in the context of a request for contraception or abortion. A law requiring the doctor to inform the police inevitably conflicts with the doctor's duty of patient confidentiality. That may not be an issue where young children are concerned: it certainly would be in the case of teenagers entitled to expect medical confidentiality. That was the rationale behind the landmark decision in Gillick v. Norfolk Area Health Authority (1986) in which the House of Lords ruled that a doctor could prescribe contraception to underage girls without telling their parents. In every case where a teenage girl under the age of consent asks for contraception the doctor must have grounds for a strong belief that a sexual offence has recently been committed, or shortly will be. It would be extraordinary if the doctor was to be forbidden from exercising his professional judgment in such circumstances.