The first time Heidi Marney took a bath in her new, temporary home, she felt she was being watched. “I had this overwhelming sense that there were eyes on me,” she says. She remembers scanning the room. “It was a big, double bath and above, on the wall, there was a TV with a device hanging down with a flashing red light.” Marney sent a photo of it to a friend who assured her that it was a dongle and said he had one too so that he could get Sky in every room.

“Logic told me that, if someone was filming me, there’d be a camera in my bedroom,” Marney continues, “so I went to my room and looked everywhere – the wardrobe, the lights; I was meticulous. There was nothing, so I told myself I was being ridiculous. My landlord was the kindest human you could ever meet. He would never do that.” She pauses for a second then sighs. “I’ll never ever ignore my instincts again.”

This happened in December 2019, when Marney had moved into Robert Holden’s rural home, a former farmhouse in Sowerby Bridge, West Yorkshire. Marney had known Holden for a decade – he was her half-sister’s uncle, so she had long viewed him as a family member. Holden was also well known in the area, a councillor who had won awards for his services to the community. “He coordinated flood relief, he fed elderly people on Christmas Day, he mowed little old ladies’ lawns,” says Marney. And now that she was at a low point, temporarily homeless after leaving a difficult relationship, Holden had offered Marney and her 16-month-old daughter a room in his spacious house while she got back on her feet. (It was something he had done many times for many others, taking vulnerable people into his home.)

Aside from that first, fleeting discomfort, the arrangement seemed to proceed well. “He’d make me a cup of tea of an evening and I opened up to him about my struggles,” says Marney. “He was intelligent and compassionate. I couldn’t praise him enough.”

She stayed for 11 months and towards the end, as Marney began to think about moving on and dating again, she felt Holden’s behaviour change. “He didn’t like it. He was acting like a weird, jealous boyfriend,” she says. When she discovered that he was tracking her through the Find My app, she called her aunt, a police officer, who advised Marney to check the home for cameras. “I sent her a video of the bathroom and she screen-shotted a sensor attached to the wall and asked: ‘What on earth is that? Why is there a sensor in the bathroom?’”

Marney took a kitchen knife and, balancing on a stool and two paint pots, reached up and prised the sensor apart. Inside, she saw the words “camera” and “microphone”. “I just completely and utterly froze,” says Marney. “It was like holding your breath. What on earth happens now?”

When she Googled the device’s serial number, she saw that the “sensor” was a camera, specially designed to avoid alerting the subject that they were being filmed. It had gone out of production two years previously, so had clearly been there a while. In fact, it later emerged that Holden had been filming women through hidden cameras for almost 15 years, creating an extensive digital library neatly organised under their names. Last September, he was jailed for six years and two months.

Holden’s voyeurism conviction is one of the few to make national headlines – but local news reports offer an alarming insight into the possible scale of this behaviour. Just this month, a doctor was jailed for filming guests at his Glasgow Airbnb for more than three years, through cameras in bedrooms and bathrooms disguised as air fresheners (one pointed at the loo, the other at the shower) and a smoke alarm. Other UK cases include photographer David Glover, who filmed more than 100 women using covert cameras in his studio changing rooms; Adam Devaney, who used a camera disguised as a pen to film colleagues in the toilet of his North Yorkshire workplace, and Adam Dennis and Robert Morgan, who used hidden cameras to film more than 5,000 people in swimming pool changing rooms and toilets in London and Surrey, then shared and traded the images online.

January to December of last year saw a 24% rise in reported cases of voyeurism and exhibitionism (crime statistics unhelpfully combine the two) in the UK. This is partly why the government is attempting to tighten legislation around hidden cameras, which are easily available in specialist spy stores, as well as on sites such as Amazon and eBay, and often made to look like clocks, adapters, photo frames, humidifiers, even disposable coffee cups.

At present, UK law defines voyeurism as nonconsensually observing or recording someone during a private activity for sexual gratification or to cause distress. Under proposals in the Crime and Policing bill, it would become a criminal offence to install equipment intended to take intimate images without someone’s consent. Motive wouldn’t be a factor – and even if no images were taken, installing a camera for this purpose would become a crime. For Marney though, this isn’t nearly enough. “How are those cameras even legal?” she asks. “The potential for abuse is so huge and obvious. It’s far more common than people would think.”

Dr Vicky Lister, a research fellow in the School of Psychology at the University of Kent, confirms that the cases we hear about represent the tip of an iceberg. Many that come to light have gone undetected for years – and few result in prosecution. In 2020, out of more than 10,000 reported cases, fewer than 600 reached court. As part of her PhD, Lister interviewed men in UK prisons for voyeurism offences (there are no women serving time for this crime). Many had used covert cameras, including one disguised as a shampoo bottle in a public shower. “It’s scary, isn’t it?” she says. “As soon as you start digging, you start to realise. The men I interviewed were saying: ‘Everyone’s probably been a victim at some point.’”

Research on prevalence of voyeuristic behaviour is patchy. “A population study in Sweden suggests a lifetime prevalence of voyeurism of 11.5%,” says Lister, “but smaller non-population studies across lots of different countries, including the UK, generally estimate higher Even [such estimates] are likely to be an underrepresentation, as there’ll be people who won’t admit it to a researcher.” There’s every reason to believe that the technology now available to facilitate this will lead more to do it. One study in Canada found that 79% of participants would engage in voyeuristic behaviours if there was assurance they would not be caught.

Lister is hoping that her next research focus will be voyeurism as a “gateway crime”. Does it lead to physical sexual assault? Some studies of rapists and sexual murderers have revealed a history of voyeurism – up to 45% – but that doesn’t necessarily mean one has caused the other. “We do know that voyeurism is addictive and compulsive,” says Lister, “so people who’ve done it once will generally keep doing it until they’re caught. Unfortunately, there’s a stark lack of literature on this whole topic. I think it’s because it’s ‘noncontact’ and seen as a victimless crime – until you’re the victim.”

For Fiona*, learning that someone filmed her while she was in her bedroom, having sex with her girlfriend, has had a lasting impact. In December 2023, she was contacted by police in Aberdeen who informed her that they had uncovered indecent images of her, taken by an electrician, James Denholm. He had used hidden cameras to film women (some of them his customers) in their bedrooms, bathrooms and pub toilets for over a decade. “By the time it came to light, I hadn’t lived in the flat where the images were taken for five years and I wasn’t dating the same person any more,” she says. “It was so long ago and I have absolutely no idea if he did some work for us or where the cameras were or how it happened. I know that he lived a five-minute walk from our house.

“It’s so grotesque and inhuman,” she continues. “It makes me feel so angry, so embarrassed and mortified and so, so exposed. It has really made me distrust men I don’t know. I’d feel very uncomfortable letting anyone come and carry out work inside my home. I’d need to watch them constantly. My blinds are closed 100% of the time. I never open them now.”

Fiona also checks for cameras in public toilets. “I avoid using them if I can but if I am in one, I will check everywhere – plug sockets, mirrors, cracks in tiles. It has made me so paranoid and anxious.”

Marney experienced similar emotions. “Knowing that he had been watching me felt awful – I felt shameful, I felt disgusting,” she says. “I remember staying at my new partner’s after this had all happened and taking a shower,” she says. “He had all these fancy water gadgets on the ceiling. My brain was saying, ‘Are they cameras? Is he watching me?’ I just fell to the floor, crying my eyes out.”

Although UK laws around voyeurism – and the proposed changes to the Crime and Policing bill – focus on the taking of intimate images, this doesn’t cover all the harms caused by hidden cameras. They can also be weapons of control. Emma Pickering, the head of technology-facilitated abuse and economic empowerment at the domestic abuse charity Refuge, says that many women they support have been spied on by current or former partners.

“Most cases we see involve hidden devices – listening, tracking, filming or sometimes all three,” she says. “It’s really difficult to help someone conduct sweeps of their home as [cameras] are designed to blend into a domestic setting. They look like everyday items. We’ll be asking if all the plug adapters work and if the remote control is really connected to the TV.” One survivor uncovered 80 spycams in her home.

An abusive partner can use the footage in various ways, says Pickering. “In one case, he was gathering intimate images and putting them online, profiting financially. Others use it to monitor everything someone is doing, who they are seeing, how they’re spending their time. With that information, they can gaslight and control and stay one step ahead.”

This is what happened to Linda*, who was in an eight-year relationship with an abusive man. “At first, he was charming and attentive but the control started subtly,” she says. “First, he convinced me to delete my social media because it was ‘bad for my mental health’. Eventually, I stopped going out with my friends as it caused so many arguments, it was easier not to.” Isolated, home alone, she would sit down to watch TV and have a cup of tea and he would text to ask, “Enjoying your cup of tea?” If she went to answer the doorbell, he would message, “Who was at the door?”

“I was so confused,” says Linda. “It was like living in a television show – like it wasn’t actually my life. I tried sitting down at different times in case he was just guessing my routine but he always knew. He seemed to know my every move.”

Linda uncovered the two tiny wireless cameras by accident while deep-cleaning. One was on the mantelpiece, the other in a light fitting. “I just felt sick and disbelief,” she says. “Why? In our home?” When she confronted her partner, he insisted that they weren’t cameras, then they quickly disappeared. “A couple of months later, I found them hidden in a different place,” she says.

Although Linda escaped the relationship when it escalated into physical abuse, her former partner continued to stalk her, threaten her online and drive past her place of work. He also left some of her clothes on her doorstep – since Linda had escaped in a hurry – and it was only later that she found the same tiny camera sewn into the lining of her returned coat.

It’s very hard to secure convictions for these cases. “There are usually no consequences for the perpetrators,” says Pickering. “Someone can claim that the cameras were in the house as a security measure, and that their partner consented to them being there. The threshold to removing evidence stored on a perpetrator’s phone or hard drive is very high and there’s also a huge backlog. Even when [material] is seized by police, there has usually been plenty of time to remove any incriminating evidence.” Attempts by Refuge to engage with manufacturers and suppliers of surveillance technology have not enjoyed much success. “It’s completely lawless,” says Pickering. “We need to be looking at why these things are available when they are causing so much harm.”

Linda agrees. “They are marketed as harmless gadgets, but in reality they’re used by stalkers and abusers,” she says. “There’s no regulation, no safeguarding. Why do they need to be hidden? Why can anyone buy them? I don’t ever feel safe now. I’m hypervigilant, it’s with me the whole time. The government should listen to women like us. It’s not that we’re paranoid – it’s just that we know what’s possible.”

* Fiona and Linda’s names have been changed.

• In the UK, call the national domestic abuse helpline on 0808 2000 247, or visit Women’s Aid. In the US, the domestic violence hotline is 1-800-799-SAFE (7233). In Australia, the national family violence counselling service is on 1800 737 732. Other international helplines may be found via www.befrienders.org.

• In the UK, the National Stalking Helpline is on 0808 802 0300 or email via its inquiry form. In the US, resources are available at stalkingawareness.org.