Sara Trevelyan was a young medical graduate when she first met Jimmy Boyle, the man who would become her husband.

It was the late 1970's, and the prison cell he welcomed her into was decorated with green floral print wallpaper with matching curtains framing a small barred window.

Jimmy was there, standing next to his bed, dressed in his denim dungarees and prepared for lunch.

On a table he had set out what he called a "Gorbals salad" for them both, complete with a fresh loaf of bread he had baked himself.

If Sara had been expecting anything, it wasn't this. She certainly hadn't expected to fall in love.

Jimmy was the man labelled "Scotland's most violent criminal", the gangster who had fought and slashed his way through the streets of Glasgow and into a prison cell, serving a life sentence for murder.

Sara was the public-schooled English psychiatrist, who, even in her 20's says she had "an interest in learning about people from the inside".

But, as she describes that first meeting in her newly published book: "His face was fresh and alive. He was physically smaller than I had expected, but his compact physique was bursting with physical strength and energy. He spoke rapidly in a strong Glasgow accent. I was swept away on the stream of his words, and it seemed we instantly connected. Despite the differences in our backgrounds and circumstances, we understood each other."

In a way, Sara's story begins and ends with a book. Her first interest in Jimmy Boyle was sparked after she bought his own book on a whim at Inverness railway station to give her something to read on the train, and she was so taken with it that she wrote to him, asking to see him.

This week, a different book lands in her hands, though one of the main characters remains the same.

Decades have passed, but Sara has now taken the step to commit her own personal account of marriage to and divorce from Boyle, who is now a millionaire writer and artist with mansions in Antibes and Marrakech.

Over the last few weeks, Sara has been speaking with journalists, agreeing to interviews she has rarely given over the last three decades.

She had one of the most notorious marriages of the 20th century, yet unlike some who marry convicted criminals, she never sought publicity nor wanted attention.

She is comfortable too, for all titles to be dropped. "I prefer to be called by my first name, Sara," she says. "It's simple and straight forward."

While slightly nervous, she is calm too in speaking of her decision to share her story now.

"Why now is a good question," she says. "It started off when Jimmy was celebrating his 70th birthday, and it was a good opportunity to look out all the old photographs.

"While I was doing that I discovered all my old journals and in them was a description of my wedding day.

"I just felt it was a story worth remembering, a story worth telling and celebrating really, of what we both put into our marriage."

Sara Trevelyan's wedding day was different than most. Instead of a church, her first stop was Barlinnie prison to pick up her groom.

From there, a little Volkswagen Beetle carried them onward to Balfron register office and the awaiting media frenzy.

Jimmy was big news. At 20, he was known throughout Glasgow as a Gorbals hard man. By 23, he was one of Britain's most wanted criminals.

Police had tried to pin two murders on him before he was found guilty in 1967 for the murder of fellow gangster William "Babs" Rooney, and sentenced to life imprisonment with a minimum 15-year sentence.

He always argued his innocence, but was unwilling to name the actual killer, and his subsequent time in Scottish prisons did not go smoothly.

As one of the first high-profile figures to be convicted of murder following the abolition of the death penalty, Jimmy was a challenge.

He was involved in riots, assaults, prolonged solitary confinement, dirty protests, punishment cells and cages, until finally he was transferred to the Special Unit at Barlinnie which was an experimental scheme to help rehabilitate prisoners.

There he discovered art, writing and, eventually, Sara.

In later interviews with the Herald, he says he knew how much he needed her. ''Inside her was the person I desperately needed at that time," he said. "She adored me, loved me for who I was."

He added: ''She taught me how to love, she absolutely taught me how to love.''

Jimmy went on to become a highly articulate artist and writer and the man who Sara was more than happy to marry and have their two children with.

Her description of their eventual divorce is without bitterness or resentment, rather a tale of forgiveness and compassion.

"Sometimes, when a marriage ends, you can feel like it's a failure, but I prefer not to see it that way," she says.

"I spoke to Jimmy about my writing the book and to give him credit, he said he'd support me. He read a draft and I think it was hard for him.

"I'm sure there were some chapters he would have rather I kept closed. But I'm glad that he read it and am really touched that he said he would support me with it.

"That is the best of what we've shared together. There were the messy bits but at the end of the day we came from very different backgrounds.

"Perhaps it isn't surprising that after 20 years we wanted different things and had to let go of each other."

Jimmy continues with his life abroad and their children have their own lives too.

Daughter Suzi, 31, is an interior designer, and son Kydd, 29, is a financier involved in social impact investment.

It wasn't until some time after Jimmy's release from jail in 1982 that their marriage faltered.

The couple had founded the Gateway Exchange, an experimental arts centre in Edinburgh for ex-offenders, drug addicts and those with mental health problems, but it was an exhausting project.

As Jimmy went down one path away from the past, Sara in her own way went another.

Years on, her memoir titled Freedom Found documents her journey through it all.

"Sometimes it's only later on that we realise what we carry inside," she says.

"One of the main themes in the book is following your heart. That can sound straightforward, but it is far from that given the situations your heart can lead you into.

"I've always believed it's important to listen to the inner voice and follow it.

"I've made decisions in my life that other people might have thought really strange, but they have been right.

"It's very easy to label people. Looking beyond the label, to see the person, that has been a main part of my journey with Jimmy."

Freedom Found: A Memoir by Sara Trevelyan is published on March 6, available from Scotland Street Press