The appearance of David Cameron's nanny in naked pictures posted online should see the issue of "revenge porn" become a greater priority for the Government, a charity has said.
The carer for the Prime Minister's children was shown in "overtly sexual poses" across at least five pictures on three adult websites, according to reports that emerged over the weekend.
It has raised concerns of a "worst-case scenario" whereby the nanny, who has accompanied the family on foreign holidays and is said to be close to Mr Cameron's wife, Samantha, could have been blackmailed over the images.
Police have reportedly been called in to investigate the incident after the woman, who has not been identified, said she believed the pictures were posted by one of her ex-boyfriends.
The photographs appear on one site next to links allowing members to buy further access including videos and webcam chats, the Sun reported, though the woman's real name and details are not featured.
While the leaked images highlight security issues for Downing Street, they also come as a high-profile example of the wider problem of "revenge porn", where former partners post sexual images online and then often extort victims for more pictures, money or worse.
Laura Higgins, helpline manager at the UK Safer Internet Centre, said that cases can involve pictures posted with links to people's Facebook profiles and messages to their families and employers - and that security was "clearly an issue here".
She told The Independent: "I'm not saying that there was necessarily a risk to [David Cameron's] children, but obviously this person is potentially going to use the fact that she is in job she's in for their own gain.
"We regularly see extortion involved - and in this case it is clearly taking it a little higher - but really this can happen to anybody."
Ms Higgins said her organisation, a partnership of three leading online safety charities, had seen the issue of revenge porn "blow up really quickly" and that reported cases were likely "just the tip of the iceberg".
She said that with much more to be done by the courts, police and Crown Prosecution Service on the issue, she wanted to take something positive from an incident "so close to home" for the Prime Minister.
"I hope this case starts a conversation," she said. "I was personally involved in giving evidence following David Cameron's comments about internet security last summer, and I was able to give them specific examples of why this is an issue.
"But I think the fact that this is happening so close to home means it might well move up the agenda - which is a good thing, because we need the Government to work with us on this."
Downing Street refused to comment on the pictures, but a source close to the nanny told The Sun: "She's horrified these profiles have come to light and is mystified at how they got there. She insists it was nothing to do with her and must be down to one of her ex-boyfriends.
"It is worrying that someone would go to such lengths. She realises that the worst scenario could have been if someone had used the stuff posted on there to try to blackmail her."