Think of the victim of a sex crime. It’s a woman, isn’t it? Maybe a girl. Now imagine a perpetrator. You are almost certainly picturing a man.

We have very firm ideas of gender in sexual offending. And with good reason. Rapes and sexual assaults are overwhelmingly carried out by men and boys, and mostly, but not exclusively, against women and girls.

Police Scotland this week issued its half-yearly crime statistics. They include the latest wave of the tide of reporting sexual offending to hit Scotland.

Detectives were told of more than a thousand rapes between the beginning of April and the end of August, a 12 per cent rise from the same period a year before.

Only gradually are police numbers starting to reflect the sheer volume of sexual - and physical - violence against women.

But, for the first time ever, the latest statistics include a new offence, disclosing or threatening to disclose an intimate image.

There were 114 such cases in just a few weeks since a specific offence was created. But this new crime, overwhelmingly online, far from always fits the normal breakdown of male perpetrator and female victim.

Social worker Daljeet Dagon of Barnardo’s has long noted that attracted older women have been used to lure boys in to prostitution or other abuse.

Now she says the same trick is being employed for webcam blackmail, so-called sextortion.

She said: “Often criminals are operating abroad. They think distance can prevent their identification and capture.

“Sextortion often begins with an inappropriate approach from a very attractive female.

“This is very similar to the sexual exploitation of boys and young men, through a trusted adult and that is most often a woman.

“These women will flatter you and try to engage in an intimate chat. Once this conversation comes to sex, they will encourage you to engage in cybersex with them. They will often go first, Expose themselves and and commit a sexual act on themselves.

“That is to make you feel at ease, to make you feel it is the most normal to do so too.

“As soon as you have exposed yourself, they will start to make demands.”

She added: “We came across a 16-year-old young man who chatted and video called for hours with a woman and started to build a relationship, build trust and felt this person knew him and had warmed to him.

“Eventually he masturbated on camera. At the end of the call he was asked to send £5000 to Western Union or the video would be shared. He was savvy, he contacted Childline. The police established the person he was talking to was in Indonesia.”

Ms Dagon wants suicide protection for victims. But she also suggests a culture change among adults.

She said: “Telling a young person that what goes online stays online is not always accurate and can be damaging. Out of context, it can remove hope.

“We need to raise awareness of dangers but we have to accept that children make mistakes. We all did.”