Robin*, a student also working as a sex worker, signed up to National Ugly Mugs in 2013 to report that he was raped by a client. The circumstances were almost identical to an incident that had been reported to our charity two weeks earlier. The only difference was that the sex worker who reported the earlier incident managed to get away without being sexually assaulted. If Robin had signed up a few weeks earlier, we could have sent him an alert warning him to avoid the man who raped him.

This is far from an isolated incident. National Ugly Mugs deal on average with 60 incidents of crime against sex workers per month, including about 10 rapes. A survey in 2015 found that 47% of sex workers who responded had been victims of crime, including rape and robbery, while more than a third (36%) had received threatening texts, calls or emails. Almost half of sex workers said they regularly feared for their safety.

Sex workers around the world are frequently targeted by dangerous sexual predators, in large part because of the quasi-criminalised context in which they are forced to operate and the stigma attached to their work. For many, reporting to the police just isn’t an option. While almost 2,000 reports have been made to National Ugly Mugs since July 2012, only 25% of the victims were willing to formally report to the police. We need a way to fight the stigma and end violence against sex workers – and that’s where our charity comes in.

The first scheme to warn sex workers about dangerous individuals started in Australia in the early 1980s. Sex workers shared handwritten descriptions of dangerous perpetrators, nicknamed “ugly mugs”, among themselves. Inspired by this simple solution, other local schemes sprang up around the world, including in many UK cities, as hand-drawn pictures and descriptions written on scrappy pieces of paper were passed from person to person.



But both sex workers and the offenders who target them are becoming increasingly mobile, which makes sharing information quickly and accurately more difficult. The case of Matthew Byrne – who was convicted in 2010 of subjecting four women to extreme physical and sexual violence in the Liverpool area – highlighted the limitations of localised schemes. He was only caught after a chance telephone conversation between the manager of a sex work project in Coventry and her counterpart in Liverpool revealed that the same man had been systematically targeting women from both cities, which sparked a police investigation. Two years later, in 2012, the UK Network of Sex Work Projects set up National Ugly Mugs, the first national scheme in the world.

Austerity​ has meant a vast increase in the demand on charities and a reduction in funding for our work

National Ugly Mugs uses an online reporting system, texts and email to create a network connecting thousands of sex workers and hundreds of support services. We take reports of incidents from sex workers and produce anonymised warnings which are sent directly to other sex workers and support projects throughout the UK. With consent, we share anonymous intelligence with the police and, if possible, support sex workers in making full reports. Our aim is not just to improve the safety of sex workers, but also to increase the reporting of crimes, so that those targeting sex workers can be identified, arrested and convicted.

Almost half of sex workers who receive our alerts have avoided a dangerous offender as a result. The warnings work; the challenge is getting them to as many sex workers as possible.

Working for a small charity, particularly one which supports some of the most marginalised people in society, can feel like constant firefighting. But technology can have a transformative impact, particularly during these times of austerity which have brought about both a vast increase in the demand on charities and a reduction in the resources available to fund our work.

Charities need to learn that if we don’t find a way to integrate technology into our services we will cease to be relevant to many of those we exist to help. National Ugly Mugs is an example of how utilising even the most basic technology can have a huge impact. We’re now piloting a project that allows sex workers to share safety information among themselves using a smartphone app, which won the community impact award at the 2016 Tech4Good Awards. From the pilot we learned several important things about how sex workers preferred to use the technology, and about challenges such as language barriers, which will inform how we refine it. We’ve got to make sure that the technology we use is designed for those who need to use it.

Slowly but surely we are making a difference, as Julie*, a female sex worker, can attest:

I arranged business with a client. He was waiting in a car and the number plate matched one I had been sent by text, which said he was a violent robber. Because he hadn’t seen me I walked away. It was a lucky escape.

*Some names have been changed

Alex Feis-Bryce is chief executive of National Ugly Mugs and a digital fellow with the Centre for Acceleration of Social Technology. Find out more about the UK Network of Sex Work Projects, one of the winners at the 2014 Guardian Charity Awards, here.

Talk to us on Twitter via @Gdnvoluntary and join our community for your free fortnightly Guardian Voluntary Sector newsletter, with analysis and opinion sent direct to you on the first and third Thursday of the month.