The rape, and subsequent death, of a physiotherapy student in India has rightly drawn attention to the country's appalling levels of sexual violence. Here in Britain, although attitudes towards such crimes are less overtly misogynistic, the gulf between the number of people who are sexually assaulted and the number of prosecutions, let alone convictions, nonetheless remains disturbingly wide.

That the latest figures suggest nearly half a million adults – most, but by no means all, of them women – suffer some kind of sexual attack each year is bad enough. That barely more than one in 10 of the incidents is reported to the police is an indictment both of legal procedures that too often fail the victims and of a culture that, for all its avowed modernity, still leaves too many blaming themselves for the wrongs perpetrated against them.

In fairness, there has been some progress. Many areas do now have specially trained police officers for sexual crimes, and specialist prosecutors are also more common than they were. Neither is yet the norm, though. Meanwhile, despite rises in both reporting and conviction levels, the advances are slight in comparison with the scale of the problem. And sexual allegations are still designated "no crime" more than twice as often as are other offences. Altogether, many questions remain as to the effectiveness of investigation methods.

Police practices are just one part of issue. By their nature, rape cases are tricky for a legal system founded upon "innocent until proven guilty" and "beyond reasonable doubt". Not only is one person's word often pitted against another's, with no witnesses; the crime is not the act in itself but the intentions of those involved.

Acknowledging the complications is not to say that no improvements can be made. Far from it. Victims may no longer face cross-questioning by their alleged assailant in court, but many still baulk at an ordeal of a process that can be almost as much a trial of the accuser as the accused. Hardly less egregious are the extraordinary lengths of time involved. With the average rape case lasting a gruelling 22 months, is it any wonder that many victims choose to avoid a trial? Alongside a systematic review of police procedures, a shake-up of legal processes that take little account of the peculiarly traumatic nature of the crime is also long overdue.

Weaknesses in the police and criminal justice systems are only part of the trouble, however. Although a mere 15 per cent of the most serious sexual assaults are reported to police, more than a quarter of victims tell no one at all. Here, indeed, is the nub of the matter. For all the well-rehearsed dangers of dark streets and walking home alone, the overwhelming majority of serious sexual offences are perpetrated by attackers who are known to their victim, and most of them take place in a domestic setting. As the Jimmy Savile scandal has made abundantly clear, perpetrators can often rely on victims' shame and fear of being disbelieved to keep their crimes hidden; what works for a celebrity DJ is no less applicable for a partner, family member or supposed friend.

Perhaps there is an upside to the Savile revelations, then. The several hundred alleged victims who have felt emboldened to come forward may help chip away at the stigma – real or imagined – that still does so much to hamper the fair treatment of sexual assault. Changes in police and legal procedures are still sorely required, but there is also a cultural issue here. While Britain is not India, our approach to sexual crime is no model of social progress either.