The first warning Tamsin Smythe had of the Ashley Madison hack was in July 2015, when her phone began beeping incessantly in the middle of a business dinner.
Tamsin, a single business consultant from Virginia, had been using the website for what she terms "afternoon delight". Specialising in crisis management, she knew at once a big news story was about to break. She just had no idea how she would be caught up in it professionally and personally.
"My phone started blowing up with people sending me messages," she says. "I thought, did the market crash? And then I read what was happening. People don't realise how exposed they are - how much personal information is out there.
"But I'm a strong woman from the South. So you have a little shudder to your knees. But then you go into battle."
One year on, Tamsin is sanguine about the events of last summer, which are investigated in Sex, Lies and Cyber Attacks, a new Channel 4 documentary to be aired next week that explores the effect of the affair on its members, and on attitudes to web security. Earlier this week, a report from the Privacy Commissioner of Canada and the Australian Privacy Commissioner heavily criticised the company behind Ashley Madison Avid Life Media (ALM), which was rebranded as Ruby Life in July.
Ashley Madison, of course, was not any old website - not a parents' forum where losing one's anonymity might be considered annoying, or even an online shopping channel where bank details might be at risk. It was a dating site set up for people who wanted extra-marital relationships, and it revelled in its own notoriety with a slogan which read: "Life is short. Have an affair."
Whilst many found its premise of enabling infidelity morally dubious, its founder, Canadian Noel Biderman, was consistently unapologetic, saying in April 2014: "Long before I launched Ashley Madison [in 2001] there were affairs, and long after I am gone there will be affairs, I'm just trying to help people have the more perfect affair."
The site was reported to have 37 million members in 40 countries, including 1.2 million Britons at the time of the hack.
It's now emerged that many using the site were single, and wanting a non-committal fling.
Christopher Russell was separated from his wife when he signed up. "I was working a lot. It was hard to meet people," he says.
"Plus, these were hook-ups, not dates - so there wasn't any risk of getting hurt. Everybody knew where they stood."
However, not everyone could stomach the sight of Biderman making a reported $55 million a year from the site. A group called the Impact Team posted a 30-day warning to Biderman and Ashley Madison's parent company Avid Life Media to close the site down in July 2015. The hackers have never been identified but many experts believe it bore the signs of an insider job.
When that was ignored, a few client names began to appear online, and then on August 18, the hackers dumped a 9.7 gigabyte file called "Time's Up!" on the dark web that held names and emails of bankers, civil servants, UN peacekeepers and Vatican employees.
Two days later, a huge tranche of internal emails was placed online. This revealed the identity of many users who had had to pay a $19 fee to have their personal information permanently deleted from the site, even those who were joined up as a joke or as a form of revenge.
The following months saw a wave of blackmail attempts, divorces, a public outing on Australian radio, and the suicide of a Louisiana pastor. The law firms Charney Lawyers and Sutts, Strosberg LLP filed a $576 million national class proceeding on behalf of all Canadians who subscribed to Ashley Madison and whose personal information was disclosed to the public. The named plaintiff was Eliot Shore, a disabled widower from Ottawa whose wife had died of breast cancer. He never met anybody in person from the site.
Meanwhile, Noel Biderman, who had told an Australian chat show his wife Amanda would be "devastated" if he had an affair, was revealed to have had multiple illicit engagements. (The couple are understood to still be together.) He stood down as chief executive and the company vowed to install the best security.
Tamsin, who had had several relationships through the site, was contacted by friends and former lovers. Wives, too, wanted to talk to her. "They were devastated," she says.
Not everyone who used Ashley Madison was genuine like Tamsin. The hackers suggested up to 95 per cent of users were male.
An investigation by the tech site Gizmodo found that the site was populated with more than 70,000 bots pretending to be female users and contacting hopeful men. The ratio of men checking messages to women checking messages was 13,585:1.
Christopher Russell says that he contacted 200 profiles and spoke to only one actual person.
The Channel 4 documentary suggests it may also have been a cheesy front for more dubious dating sites including Arrangement Finders, a site for young women to find older men where the relationship would involve a financial reward - its tagline is "Intimacy with a twi$t".
Gina Smith, editor-in-chief of the independent media site ANewDomain.com, who covered the story, says: "It appears to be a sprawling collection of websites, which appear to be designed to get people to come in to do other stuff. And that stuff doesn't seem to have a lot to do with dating."
Could Ashley then have been described as a gateway drug, where men might drift from speculating about an affair, or feeling frustrated when they couldn't contact a real woman, to accessing other services such as escort sites?
It was "a good site for people to get their feet wet," says Tamsin.
Ashley Madison is still going, with the new tagline Find Your Moment, claiming more than 48 million members worldwide.
The company has beefed up its security - but the hack left many asking questions about online safety.
Will the leak make people think twice about seeking casual, even extra-marital relationships online?
Harley Street psychotherapist and relationships expert Christine Webber says some men and women believe by using these sites they are saving their marriages, by not having a conventional affair, or finding relief from a dire relationship which they may feel they are tied to.
"I also know of situations where people want special sexual services that they can't get at home, which might be as basic as oral sex."
Certainly, it has not put Tamsin Smythe off websites like Ashley. "I feel the lifestyle is incredibly empowering for women, and it allows women to set the rules and call the shots and websites are the best way to find this type of relationship."
Rob Segal, chief executive of Ashley Madison's new parent company, Ruby Life, announced a total repositioning of the business in July, and said earlier this week that the company has voluntarily entered into compliance agreements with the Australian and Canadian government officials. "The company continues to make significant, ongoing investments in privacy and security to address the constantly evolving threats facing online businesses. These investments are the cornerstone of rebuilding consumer trust over the long-term," he said.
Chairman James Millership said the company was overhauling other business practices, including transparency and accuracy, to make it harder for users to join without a legitimate email address.