"I went to Cross Creek in 1955 - I was on the last excursion of those trains up the Rimutaka Incline before it closed," said Mrs Swadling, a former teacher.
"My parents said it was an historic event and that I ought to go. I was 17.
"I thought to myself, 'Do I really have to go on this trip?"'
The young Mrs Swadling was enchanted - and would go on to make several train trips to Wairarapa, stopping at Featherston's iconic Fell Engine Museum and the Rimutaka Rail Trial, bringing family, friends and school groups.
"My awareness of that history continued. So when I went to Whitireia, I thought, 'Why not write a novel about Cross Creek and the railway line?"
In Cross Creek Return, the central character, George, has a premonition of the Rimutaka Incline disaster - occurring when a train on its way to Wellington was hit by strong winds passing the Siberia Curve.
The wind blew the front three carriages off the line, throwing the passengers onto the cliff side below, and killing four children.
In the book, George survives the disaster, but is traumatised by the experience.
"The trauma has quite a dramatic impact on his life," said Mrs Swadling, who published a hardcover children's book, Legends of Aotearoa: New Zealand Birds, in 2006.
"The book is a combination of history that a lot of people experienced, coupled with the drama of what can happen to a child."
While researching for the book, Mrs Swadling spent hours studying old newspaper articles and photos from the era, pored over historical accounts of the Rimutaka Incline and even rode a steam locomotive between Wellington and New Plymouth to get the feel of the "heat and the rhythm" of the engine.
She visited the Fell Museum several times while doing her research, where she received advice and history lessons from some of the museum's original founders.
"They were extremely helpful," said Mrs Swadling.
"They helped my very non-technical mind understand just how those trains worked. Sadly, a lot of those people died before the book was launched. So, the book is a tribute to them in a way."
She said she is especially grateful to her writing tutor Mandy Hager, who helped her with a second draft of Cross Creek Return when she re-enrolled at Whitireia in 2012.
"The Whitireia course really helped lift my writing.
"Mandy helped me improve my technique, but was very encouraging. You didn't feel like giving up."
The book was self-published, with the book design by Porirua editor and designer Stephanie Drew. Cross Creek Return will be launched at the Fell Locomotive Museum, between Lyon St and Fitzherbert St, Featherston, at 2pm on Sunday. Phone the museum (06) 308 9379 if you wish to attend. .