Despite the odd Germanic-sounding vowel – a holdover from his native Des Moines brogue – you do have to remind yourself that Bill Bryson isn't British. It's not just that he's Britain's best-selling author of non-fiction. Or that his Notes from a Small Island was chosen by BBC Radio 4 listeners as the book which best represented Britain. Or that he has spent much of the past 40 years on his adopted "small island" with his British wife Cynthia. The real tell that Bryson has properly gone native, is his self-deprecating sensibility.

Today, as we're discussing A Walk in the Woods, the writer's 1998 account of an eventful attempt to trek the Appalachian Trail – now the subject of a film starring Robert Redford and Nick Nolte – Bryson almost always sounds on the verge of an apology.

“I had nothing to do with the thing that it has been transformed into,” he says. “I sold them the rights. And when you sign the contract you give them the right to do anything they want with it. It could have been an action film with superheroes. I’m not really a central part of the process at all.”

That is, perhaps, just as well. Although Robert Redford optioned the humorous travelogue as long ago as 2005 – with a mind for an onscreen reunion with Paul Newman – A Walk in the Woods has weathered an eventful pre-production history, as various screenwriters and directors (including Harry Potter's Chris Columbus, Borat's Larry Charles, and Rain Man's Barry Levinson) became attached, then detached from the project.

“Most of the time I wasn’t thinking about it at all,” says Bryson. “I was told by people who are more experienced than I am that most books don’t get made into movies and not to count on this. I suppose they’ve been very busy trying to get financing packages and various challenging things together. It wasn’t at all in the foreground of my life until a couple of years ago when it all seemed to come together and they started shooting.”

The events recounted in A Walk in the Woods took place in the late 1990s when, having spent most of his adult life in Britain, Bryson returned to the US. He lasted eight years.

“We thought it would be a good idea to give our kids a little bit of experience of growing up in America,” he says. “I’ve always felt very lucky to have had two countries in my life. Everybody who has got that, I think, is in a favoured position. And the kids are half American. As it turned out I really didn’t like being back in America. It was a real struggle for me whereas my wife and kids loved it, loved every minute.”

Why wasn’t America for this particular American? “My feeling all the time was that this is what I used to do. It felt exactly like moving back in with your parents in middle age. You may love them and you may love to visit but you just don’t want to live with them any more.”

William McGuire Bryson was born into a newspaper family in 1951. Both of his parents were of Irish descent. “My father was bonkers about genealogy and all of my forebearers were from Ireland. My father’s side were Ulster Protestants and my mother’s side were Ulster Catholics. He knew every detail and he and my mother would make frequent trips to Ireland.

“I wish I had paid more attention to the details while he was alive. I really regret that the information is lost to me now.”

Bryson followed his parents into the family guild in the late 1970s, when he took up a post at the Bournemouth Evening Echo before moving on to the London Times and, later, the Independent.

“We worked in newspapers. It was what we did. Both my parents and my brother wrote for the local paper. It was what we talked about at the dinner table at our house. It never occurred to me to do anything else. And also English was the only thing I was any good at, at school. I never really expected to be a writer. For the first half of my life I worked as a sub-editor. Writing only came into it because when our family was young we needed to supplement our income. For things like a washing machine.”

Writing the Bill Bryson way has proved a sui generis business. He must have had some interesting conversations with publishers over the years, as he pitched subjects as varied as Shakespeare and Australia.

"I've been very lucky with my publishers over the years because they have indulged me," he says. "The British have been particularly good and rather braver. I had to fight hard for the Americans to let me do a book on Australia because they thought nobody in America wants to read a book on Australia. Luckily for me, it turned out they do. You have to follow your gut instinct with writing. The things that end up being really successful nobody can predict. Who could have predicted that Harry Potter would be such a giant success? If you think you know the next big thing, you're bound to be wrong."

Between books on etymology and science, Bryson has produced some of world's favourite travel writing, including The Lost Continent, African Diaries and Neither Here Nor There, the European memoir that introduced the pseudonymous "Stephen Katz", Bryson's former high school chum and his unsuitable hiking companion throughout A Walk in the Woods. Katz is essayed by Nick Nolte, looking as if he couldn't manage stairs, let alone the Appalachian Trail, in the film.

“When he turned up I was quite shocked. He was in even worse shape than I thought he would be. I didn’t expect him to be in really great shape. But he was a lot worse.”

I wonder how he felt watching Nolte’s Katz and Redford’s Bryson? “On the one hand I was very confident because it was Robert Redford and it was his project. I knew he wasn’t going to do anything that would embarrass or distress me. It wasn’t as if the book had ended up at some studio. So I was pretty confident I wouldn’t be disturbed.

“But, even so, when I watched the movie for the first time, while I wasn’t exactly nervous, I was very tentative. Is there going to be anything in here that I wish they hadn’t done? And I’m happy to tell you there was nothing at all. It wasn’t strictly accurate. The Robert Redford character is quite different from me in real life. But the thing they got absolutely right is the relationship between Robert Redford and Nick Nolte. They did the chemistry between those two characters brilliantly.”

Rather refreshingly, A Walk in the Woods feels like a comic corrective to the current wave of spiritual travelogues and the films they inspire. The timing, says Bryson, is entirely coincidental but his particular walk did make for plenty of incident.

“It’s a strange thing when things don’t go to plan,” he says. “In a personal sense it’s very irritating and it can be a real nightmare. But at the same time I’m often thinking about the book: Jeez, I hate this but it might read okay. If I get bitten by a rattlesnake it’s a pain in the ass, but it will make a good chapter. When you’re gathering material for a book, it’s a little bipolar that way.”

A Walk in the Woods is on general release

On the road Three of the best recent travel movies

1. Encounters at the End of the World (2007): Werner Herzog journeys to the McMurdo Station in Antarctica and contemplates "certain death".

2. Wild (2014): Reese Witherspoon got an Oscar nod for Jean-Marc Vallée’s adaptation of Cheryl Strayed’s Pacific Crest Trail travelogue.

3. Tracks (2013): Mia Wasikowska plays Robyn Davidson, a writer on a 2,700km trek across the desert of Western Australia with four camels and her trusty dog.