The Fermanagh woman talks to Laurence White about her unusual childhood, a career that took her all over the world and how at one point she feared the emotional fall-out from her work as a therapist would result in her also needing professional help.
In the Imperial War Museum archives lie details of horror mercy killings in the Burmese jungle during the Second World War which involved a Northern Ireland doctor. The medic was a member of the famous Chindit soldiers who fought behind Japanese lines during the conflict and who had to carry out a distressing order when their force was in danger of being overrun.
The soldiers could not evacuate some seriously wounded colleagues which left them with a terrifying choice. These men either faced an agonising death from their wounds or torture and then death at the hands of the Japanese forces.
The order was given for the doctor, who had been born and educated in Northern Ireland before going to England, to administer morphine to as many of the wounded soldiers as possible and then they were shot by their own side to spare them further suffering.
A fictionalised account of this event is one of the themes in a novel by Fermanagh author Sheila Llewellyn which will be published this month.
Walking Wounded draws on extensive research into the causes and treatment of Post Traumatic Stress Disorder (PTSD) among war veterans. Set in a military hospital just after the end of the Second World War it also examines what would now be regarded as a barbaric medical practice but which then was regarded as a way of treating psychiatric disorders.
The advice often given to authors is to write about what they know and the treatment of PTSD is a speciality which Sheila practiced in Northern Ireland at a renowned trauma centre after moving here in 2003.
But it was only when she retired from that post and began seriously considering a career in writing that the idea for the novel began to take shape.
She was undertaking a PhD in creative writing and thought about penning a series of short stories charting the development of PTSD treatment from the American Civil War to the modern conflicts of Iraq and Afghanistan.
As part of her research she spent some time combing through dusty copies of the Lancet medical journal in Belfast's Royal Victoria Hospital archives and came across a startling discovery - the use of brain surgery to treat PTSD and other psychological conditions.
Known as leucotomy, fairly basic tools were used to bore holes in the skull and snip away parts of the brain. Sheila says: "I was so shocked that someone had suggested that this was a suitable treatment for what we know as PTSD. It just leapt out at me that this was where I needed to put the focus of my writing."
Her novel charts the conflict between those who believe in the surgical intervention and a senior psychiatrist who sees talking therapies as the proper approach.
She realised that she must get the medical facts spot on to give validity to her novel but also accepted that she was setting it in a period much different from today.
"I had to judge what they did within the ethics of the period. They were not monsters and were convinced that this was a suitable panacea for a psychological disorder. That was what it was like in that period. Otherwise I would have been writing a cast of villains."
It was not only her latter day work that informed her choice of theme, but also her father Herbert's experience in those same Burmese jungles. He had fought there - although not with the Chindits - and had sent home letters and journals from the front line, although most of those were of a strictly personal nature.
She recalls: "Time and time again, the soldiers fighting in the jungles had to make horrendous choices leaving wounded colleagues behind. That was something my father never talked about.
"In one of the very last conversations I had with him we were talking about his life in general. He said to me that I could never imagine the horrors of that war in Burma and what the soldiers went through."
In her book she uses an unusual metaphor based on fact to convey how those horrors left so many unable to talk about the war when they came home. Before the soldiers set off to go behind enemy lines the voice boxes of the mules they used to carry equipment were cut to prevent them braying and alerting the Japanese to their presence.
Sheila, now aged 69, had an unusual upbringing. When her father returned from the war he began working for a major construction company and subsequently moved to what was then British Guiana on the northern coast of South America, taking Sheila with him.
His job was to build homes for the staff of a French-Canadian company involved in bauxite mining on the banks of the Demerara River. Sheila lived there from the age of eight to 11 and for the first year had no school to attend. She had books sent out to her from London and also developed a voracious appetite for reading, spending hours in the camp library.
After four years, her father moved to Barbados, founded his own building firm and died there in 1969. She had returned to England, where she was born, to live with an aunt and uncle - a very different couple from her father. Her uncle was a committed socialist and wanted her to study in Moscow. Her father's wish was for her to go to Oxford, something she was to do many years later.
But her initial university studies were in Manchester, a city she loved, and where she met her husband, Ken Dennison, an engineering student from Enniskillen. "In 1968, I came to Northern Ireland to meet his friends and family and we got married that year."
After their studies they went to Africa and it was the beginning of a somewhat unconventional marriage. "We had no children and both of us wanted interesting jobs. Both of us got contracts in various parts of the world which meant spending periods of time apart, but it sort of worked. After all, next year we will celebrate 50 years of married life.
"Although we had not returned to Northern Ireland, we felt emotionally connected to it and wherever we were in the world we kept abreast of what was happening here," she says.
Her quest for an interesting career took her all over the world. One of her first jobs abroad was to Iran to teach English to professionals like doctors and engineers.
"This was in November 1978 just as the revolution against the Shah had begun. I was supposed to be there for six months but only spent around half that time.
"I was in Tabriz in the north of the country which was quite Russian in outlook, with many of the revolutionaries Marxist. I was able to move about quite freely. Many of the professors in the university were leaving and the students were on strike. They used to hiss at any Americans they met - it was their way of showing displeasure.
"At one stage the British consul had to return to the UK and he said I could stay in the consulate until he returned. It was a bit surreal as there was only me and a nightwatchman in the building. That was the only time I felt a bit exposed. I had to be careful as there was an unofficial curfew and a dead body was found near the consulate at one stage."
Other jobs took her to Zambia, Singapore and east Germany but she still found time to further her education - indeed she has amassed an astonishing six degrees including a PhD. She was a manager in British Gas providing training for workers in the oil industry but it was her decision to take a psychology degree with the Open University which changed her life.
On graduation in 1995 she began work as a therapist at Macclesfield Hospital helping people suffering from Post Traumatic Stress Disorder, including families bereaved by vicious drug gangs and soldiers who had been on NATO duty during the war in the Balkans.
Sheila decided to develop her expertise and then fulfilled her father's wish to see her study at Oxford, where she undertook a post-graduate diploma specialising in PTSD. She recalls how one of the tutors had been working with soldiers who had fought in Vietnam and, like the Burmese soldiers all those years before, had witnessed badly wounded colleagues being shot rather than left to fall into enemy hands.
"That course was a formative moment in my life. I found it very satisfying to work in that area of therapy, trying to get people to assimilate what had happened to them and how to live with it," she adds. When her husband took early retirement, the couple decided to move to Enniskillen and Sheila began work at the Centre for Trauma and Transformation in Omagh where she came in contact with not only survivors of the Omagh bombing and those bereaved by it, but also others suffering psychological damage from other parts of Northern Ireland and even the Republic of Ireland.
Part of her work was training nurses in cognitive behavioural therapy in an EU-funded project which spanned the border. "That was an amazing induction to Northern Ireland for me, a really interesting and satisfying job and now with Brexit it shows why we need to keep the border porous."
She says that civilians, like those caught up in the events of the Troubles, have different problems to deal with compared to soldiers. "The soldiers coming back from war suffering from PTSD have to deal with it, but not in the theatre of conflict where the events which triggered it happened. The civilians we deal with in Northern Ireland were living in the area where the event occurred and where, they believed, those who had caused them to be bereaved or who had injured them still lived. They are dealing with abnormal things which have become normal because they have lasted so long."
Sheila admits that dealing with traumatised people is also difficult for the therapists. "I remember I used to go swimming after work and would find myself mulling over what I had listened to during therapy sessions and thinking that I might end up on my own waiting list.
"However, Omagh was a very professional place to work and we were supervised and could talk through any problems with superiors. That was not seen as a sign of weakness but instead was built into the professional activity of the therapists.
"Therapy can be a Catch 22 situation. If you become immune to what people are telling you at clinics then it is time to give up that work as you are not processing what they are going through. However, if you show too much empathy then that is damaging to you as a therapist. I don't think I ever got to that stage and I really miss that work."
She had one burning unfulfilled ambition, however - to write. And it was regular Belfast Telegraph contributor Malachi O'Doherty who helped her on that road.
"I really didn't know how to get involved. I went to Queen's University and met Malachi at an open memoir class he was taking. He introduced me to the weekly writers' group run by Ciaran Carson and one of the first people I met was award-winning poet Sinead Morrissey. I don't think I would ever have become a writer had I not come to Northern Ireland. It was the right time for me but there is great support here and people are so generous with their time and willing to help you.
"The more I write - and I write every day - the more I want to and I have never stopped for the last five or six years."
And it is writing which has been widely acclaimed. Although Walking Wounded is her debut novel, she won the P J O’Connor RTE Radio One Drama Award and the Silver Award for the Best Broadcast Radio Drama in the New York International Radio Drama Festival in 2012.
She has also been shortlisted for the Bridport Short Story prize, the Sean O Faolain Short Story prize and shortlisted twice for the Costa Short Story award.
She has received support from the Arts Council of Northern Ireland, and one high-profile fan is two-time Booker Prize winner Hilary Mantel who took a special interest in this novel and sent it to her agent who had suggested some changes.
To Sheila’s delight it was picked up rapidly by Sceptre, an imprint of Hodder & Stoughton, news which the author heard on the night that Donald Trump was elected president of the US.
It seems that momentous and unexpected events follow Sheila wherever she goes.
Walking Wounded by Sheila Llewellyn is published by Sceptre, Price £16.99. It will go on sale on January 25