Author Bill Bryson has said having Hollywood A-lister Robert Redford play him was flattering initially, but says he then "began to feel quite differently".

Bryson is referring to the big-screen adaptation based on his novel, A Walk In The Woods, which sees Redford playing him.

The book documents his journey with his friend Stephen Katz (who will be played by Nick Nolte) as they attempt to walk the Appalachian Trail.

"It was surreal for about 60 seconds," Bryson told the Radio Times about Redford. "In terms of vanity, it was terrific. But then I began to feel quite different. It was now his project."

In the movie adaptation, Bryson's wife is called Catherine, although in real life her name is Cynthia.

"It was clear from that point that this was no longer my life. It was a film about a character name Bill Bryson."

Despite hailing from America, Bryson is extremely passionate about Britain, and wrote the book Notes From A Small Island about the UK in 1995.

"Britain should be proud of its lovely landscape and the way it provides sustenance and amenity at the same time," he says.

"It's a working landscape, and yet we can also savour its beauty. That notion just doesn't exist in America. We see land as either something for amenity or for industry."

Reflecting back on his epic adventure with Katz, he says it changed his feelings about the world, not just America.

"Just how big it is. Out in the hills, where you can't see a house. On foot, you move so slowly through the landscape. Your idea of scale changes: you do 10, sometimes as much as 15 miles in a day, and that's a long, long way."

But don't expect him to be embarking on another walk like that one any time soon.

He's clear that is was the "hardest thing I've ever done" and makes no bones about the fact that "I never want to do it again".

"When I finished, I was extremely fit - by my standards. But also I felt as if my brain had been cleaned out in soapy water," he says.

Bryson has just completed another book, The Road To Little Dribbling, which will be released next month and is cited as a belated sequel to Notes From A Small Island.

A Walk In The Woods is due for release in UK cinemas on September 18.