For Swinging 70s, read Sordid 70s.

There may be some welcome signs that the recent exposure of the dark underbelly of the era of sexual liberation and the shaming of some of those involved are encouraging more victims of sexual offences to come forward in the knowledge that today their voices will be heard.

Four decades ago sex pests and child abusers were able to operate behind a conspiracy of silence. That applied especially to men who enjoyed the power that came with celebrity, like Jimmy Savile and Stuart Hall, who was convicted this week for offences committed against young girls up to 40 years ago. They did what they did because of this atmosphere of impunity. They were confident that they would never be unmasked and anyone who complained would be fobbed off or disbelieved. No longer.

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Yesterday's Scottish crime figures showed recorded crime at a 39-year low. The one area where there was a marked rise was sex offences, which are up 5% on the previous year. Such figures are always difficult to interpret, especially when there have been changes in the way offences are reported. Yet, under normal circumstances one would expect the number of offences being reported from before the implementation of the 2009 Sexual Offences Act, should now be falling. Instead, it is continuing to rise. One interpretation of the statistic is that the sight of other victims of historic abuse and sexual crimes coming forward is giving people the confidence to confront the guilty men. As Justice Secretary Kenny MacAskill put it yesterday: "Whether it was perpetrated last night or decades ago, those who did it should be brought to justice."

Conviction rates, especially for rape, are still far too low but there have been marked improvements in recent years in the handling of such cases by both specialist police units and expert prosecutors. Indeed, one argument in favour of a single Scottish police force is the ability to pool expertise in tackling sex offences, including child sex abuse.

Every era brings with it fresh evils. If "dirty old men" (and dirty young men too) thrived in the permissive culture of the 1970s, today's sexual predators cruise the internet for child abuse and rape images or pornography featuring young girls, as did the murderers of April Jones and Tia Sharp. That formed part of the backdrop to the summoning of Google, BT and other web companies and internet service providers to a Government summit on online safety yesterday.

Though child abuse images are already illegal, too little has been done to hunt down offending sites and those who use them. The industry and politicians both bear some responsibility. The former for failing to put enough effort or resources into blocking such content and the latter for cutting the budget of the Child Exploitation Online Protection Centre (CEOP). Instead of the recent mutual recriminations between the two sides, a joint determination to root out such material is required.

Pressure on the industry, which once simply blamed the perpetrators, seems to be working. BT's agreement to flash up warning signs when users try to access child abuse material and Google's investment in tracking technology show what can be done, as does the 59% rise in Scotland last year in the recording of offences involving indecent images of children.

Like the child abusers and sex pests of the past, the best disincentive is the knowledge that those who create and feed on such material can be caught, prosecuted and shamed.