Alexandra Stein was 26-years-old when she joined the O. A decade later, she fled the group, realising she had been brainwashed and unwittingly joined an underground political cult.

Stein, who was born in South Africa, spent her childhood in London with her parents who were active in left-wing politics. Aged 18, she moved to Berkeley, California, and volunteered for a free clinic for poor people. She wanted to change the world.

After being accepted by the leader of the O - a Marxist-Leninist group - she was assigned the codename Clare, and moved into a house where she lived with two other members. Instead of walls, the building had dividing screens and little privacy.

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Soon, everything from what she ate, where she slept and who she spoke to were being monitored by the leader and his “cadres”. Visitors weren’t allowed. Neither was contact with friends and family.

As part of her assessment, she revealed everything from her deepest fears to her greatest ambitions to the leader. This information was then used to control her. Two years into her membership - during which time she worked in an O-controlled bookshop and bakery - she was told to have a baby with a fellow member. After they struggled to conceive, the couple adopted two babies.

But the facade of the group’s aims began to crumble when Stein released those in the bakery ran by the O were paid minimum wage. This went against the group's apparent desire to spark a revolution and create an equal society. When she quit the bakery in protest, her partner was banned from speaking to her. Realising she had been sucked into a cult, she fled with her two children. She later learned that the leader Theo Smith formed the O a year after serving time for killing a man in the cult.

Now, Stein teaches about cults and totalitarianism at the Mary Ward Centre in Bloomsbury, London, and recently released her new book Terror, Love and Brainwashing: Attachment in Cults and Totalitarianism.

The Independent spoke to Stein to about Trump, Netflix comedy show Unbreakable Kimmy Schmidt which depicts the life of a former cult member, and how cult leaders lure in their victims.

What separates a cult from any other group?

I have a particular definition. The fundamental aspect is isolation from the outside world. There needs to be charismatic authoritarian leadership, the structure must be isolating, and the belief system total. You have to believe that system and nothing else. They say ‘you don’t need anything else because we cover everything in the universe, and everything that will ever happen’.

For instance, [US President] Donald Trump has put people in charge of the Environmental Protection Agency who don’t think climate change is real. That’s part of that. They’re suggesting that ‘you don’t need science. That's extraneous’. That’s total ideology.

Cults also use a process of brainwashing which boils down to isolating people or saying the group is the saviour in some way, or in my case will lead the revolution for a better life. Then you instil fear in members by saying the apocalypse is coming, or the foreigners are coming, or people with different coloured skin will take your job, or you have a demon inside of you. The victim is convinced they can only get comfort from the group, even though it’s actually extremely dangerous.

For people on the outside it’s very frustrating to talk to someone in a cult because they can only spout nonsense. All of those things together create groups with leaders who control someone and make them go against their own needs for survival.

With Trump, I say watch this space. There are too many warning signs to ignore. I’d call it totalitarianism. The belief system is fictional and people don’t know what is real anymore. When it was argued that more people were at President Obama’s inauguration, Trump's followers argued that the photos were doctored. Otherwise reasonable people start to get confused. Be scared!

How has being in a cult affected you?

In terms of being able to do the research it was an advantage because when I speak to other ex-members I am able to understand their experience. And a lot of ex cult members are stigmatised. I didn’t have that negative feeling towards them. I wasn’t looking at them and saying ‘tell me about how weird you are’. I took a more understanding approach.

When I wrote my first book, which was a memoir, that was cathartic because it was just me telling my story. So by the time I started my research it was mostly out of my system. The one thing I still get upset talking about are the children in these groups because it's so terribly upsetting. So it’s not that I’m cold-hearted and distant but I’m past my own experiences. It’s been 26 years since I left and it’s quite cool as a memory.

What do you think of depictions of cults in the media, like the Netflix show Unbreakable Kimmy Schmidt?

Above: The trailer for Unbreakable Kimmy Schmidt

I love that programme! If you’re newly out of a cult it might be upsetting, but I think humour is wonderful. Cults, except for the laughing cults, don’t approve of humour. That’s too much fun. I’m very much in favour of humour. When I first saw it I rolled about with laughter. They were accurate and had done their research of what it feels like when you come out. Even though I lived in the outside world and I wasn’t locked up, the control is so tight. When you come out it’s really like coming into another world. You don't know how to make decisions. And I think they capture how wide-eyed you are. I was in my group through the 1980s. And people would talk about David Bowie and I’d say ‘huh?!’ There were cultural things that completely passed me by. I didn’t have any time to listen to music or anything like that.

When Gretchen, one of the former cult members is being interviewed on TV and she tells the presenter she followed her cult leader because she was worried about seeming rude if she didn't. What did you think of that?

I think that’s really important. The thing I’m interested in is prevention education. Part of the the prevention is learning if you're feeling in a funny situation you can say no even if it's impolite. You have to teach children and young people about social norms and group behaviour and the influential methodologies.