Kate Johns: 'Prison saved me' – the fall of a City high-flyer

As a lawyer at a big London bank, Kate Johns lived a privileged life. It was being imprisoned for fraud that brought her back to reality, as she tells Charlotte Philby

Kate Johns can't remember the moment the foreman of the jury cried "guilty" – she had taken an overdose, her ninth suicide attempt since charges of fraud and money-laundering were brought against her two years earlier. "I was scared witless," she says. "As far as I was concerned, this was the end of my life."

As the high-flying general counsel for the Bank of Tokyo-Mitsubishi in London, Johns had been in charge of a legal budget of £20m a year. She was responsible for the legal affairs of the European offices of the largest bank in the world, as it was when she was arrested for defrauding her employer of millions of pounds.

"Suicide was my way of trying to negate the reality of what was happening," she recalls.

Two months after her release, Johns, now 43, has written a book about her spectacular descent from the glass towers of the City to HMP Holloway.

In it she claims prison "saved my life" and paints a picture of a toxic City environment where employees like herself and the recently convicted bank trader Kweku Adoboli are made "corporate scapegoats".

Johns' story also shines a light on the systemic failings of the criminal justice system, and offers an insight into the everyday lives of the invisible women in our prisons.

In 2006, Johns was living in a five-storey house in smart Primrose Hill. She had daily blow-dries, scoffed at public transport and was on the private lists of some of the world's biggest fashion designers. "I wanted for nothing in that sense," she says. "I'd enjoyed a very good career, and I'd become a very confident, maybe arrogant, lawyer in the process."

But within 10 days of being sentenced to five years in prison (she served half of that), the Oxford graduate was living in a cell in the healthcare unit at Holloway, one of 17 women with problems ranging from paranoid schizophrenia to Munchausen's. At the outset of her trial, she was misdiagnosed with bi-polar disorder and now blames the drugs she was given for her suicidal thoughts.

Transferred to the main block six months later, she spent most of her time in shared accommodation with up to five room-mates. There was "a real sense of camaraderie", she says, and some inventive cell decoration: "You're not allowed glue so cards and photos were stuck to noticeboards with specially sanctioned prison toothpaste … Dish cloths used as table-cloths, and a no-glass policy meant hot-chocolate and coffee tubs were used as vases, with flowers picked by staff who worked in the surprisingly beautiful prison gardens.

"We used tea-bags as fake tan, permanent marker as nail varnish, prison porridge as a face mask."

There were some chilling moments – not least when Johns was an eye-witness to an attempted murder involving two inmates – but the most profound impression, she says, is one of a group of largely disenfranchised women, whose crimes ranged from petty theft and prostitution to murder, being "in it together". It was after successes or disasters at court, Johns adds, that real friendships were forged.

Johns was born in Cardiff and took her mother's husband's name, Astley-Richards, before learning the identity of her biological father in her late teens. Richard Johns was a former Middle East editor of the Financial Times who had been a close friend of her mother, Judy. His daughter was named sole beneficiary in his will.

As a teenager, Johns won awards for her playwriting and became Thelwell Scholar of Modern History at Jesus College, Oxford, before studying jurisprudence, followed by post-graduate studies in European law. She divorced her husband, fellow lawyer Charles Gibb, in 2010.

During her time in prison, Johns refused to see a single visitor. It took her months to accept her sentence. "There is a period of denial," she says, "when all your efforts are concentrated on finding a way out".

Her lucky break came "by chance". "There was one probation officer who helped me see what had happened. It was almost an epiphany. I realised there were moral and ethical issues in my background that were troubling, which I had to face and identify before moving on." But for so many, she says, that never happens. "There is often a sense of treading water, of having a surfeit of time you have to get through."

After Holloway Johns was sent to the private Bronzefield prison, where "everything sparkled: plasma TVs in the reception, rooms with curtains and duvets. Officers wore corporate name-badges which said 'Call me Dave'." But there was dirt beneath the surface. "There were teenagers working there who'd been baggage handlers at Heathrow and check-out staff, and had done a five-week course before becoming responsible for prisoners".

Because the Freedom of Information Act doesn't apply to private companies, inmates also find themselves denied access to papers they need to prepare for their hearings. "I was approached by women for help with the most basic legal correspondence: debt demands, housing issues."

Foreign nationals constitute 20 per cent of the population at Bronzefield, which acts as both a remand centre and high-security prison. "These women are left in limbo not knowing what is happening: there is neither the time nor skills-base to allow them to understand what they're being charged with and why, and many are kept there beyond their tariff because there is nowhere to send them on to."

Johns spent her time inside studying human rights and prison law, and advising fellow prisoners.

In the end, she says, prison saved her life. Today she is outspoken about a sinister City environment where excessive risk-taking among employees is encouraged, and those involved don't see the human cost of their greed. It took the space and distance that prison afforded before she could see it. "The more one gets caught up in it, the harder it gets to walk away. If my conviction hadn't come about, I'm not sure to this day whether I'd have ever walked away."

Kate Johns: the rise and fall

* Won Playwright of the Year at 16.

* In 1998 became Thelwell Scholar of Modern History at Jesus College, Oxford. Also studied jurisprudence.

* Did postgraduate studies in European law at King's College, London.

* Joined legal department of Bank of Tokyo-Mitsubishi in 1998.

* Arrested for defrauding her employer of £7m.

* Misdiagnosed with bipolar disorder and sentenced to five years in prison in 2010.

* While at HMP Holloway, studied human-rights law and advised fellow inmates.

* Released in 2012, has written a book of her experiences and now works for Hibiscus, a charity for women affected by the criminal justice system.