"Ooh, have you seen 127 Hours?" says the novelist Carol Birch, leaning forward excitedly. It's a strange way to start talking about her new book, Jamrach's Menagerie, but it makes a kind of sense. When Danny Boyle's film was nominated for the Best Picture Oscar last month, it was a small victory for the intimate, thought-provoking stories that question how we'd act in perilous, life-threatening situations.
No arms are cut off in the course of Jamrach's Menagerie, but Jaffy Brown, very much the hero of her salty historical adventure set on the perilous ocean, has a similar conundrum. Cast adrift on the open sea, can he kill his childhood friend so that others - including himself - can live?
"They both say: 'Would you be able to do that?', don't they?" she continues. "And I don't suppose anybody really knows until they're confronted with a terrible situation. I think, sitting here in a bar in Lancaster, that I'd be an awful coward. Maybe I wouldn't... although I'm a bit put off by the prospect of watching a man cut his arm off in the cinema. Tell me, how did they do it?"
Birch has a glint in her eye, perhaps born of the knowledge that Jamrach's Menagerie is potentially a career-defining book. None other than the eminent Booker Prize-winner AS Byatt, who, as a distinguished literary critic, should know about such things, interrupted a radio discussion on Victorian literature recently to call it "one of the best stories I've ever read". Even Birch, who has been writing consistently interesting novels since the late 1980s - making the Booker longlist for her 2003 book Turn Again Home - thinks it's "probably my best one so far".
Jamrach's Menagerie, her 11th novel, begins in 1857, and is a conflation of two true stories. First of all, Birch happened upon the story of a small boy who came across a Bengal tiger in, of all places, a London street. He was, so the legend goes, so enchanted by this exotic animal, he walked up and patted it on the nose... and ended up in its jaws.
"I just kept thinking what it might do to you to be walking along the street one day and have this life-changing, life-threatening event happen to you," she says. "To be up against your mortality at such a young age would stay with you, I think."
It wasn't the only Victorian tale that was fascinating Birch at that time. She was reading accounts from the survivors of the famous wrecked whaler the Essex - on Herman Melville's desk when he wrote Moby-Dick - and, she says, a story came together.
In Jamrach's Menagerie - and yes, there also was a real London menagerie owned by Charles Jamrach, full of exotic animals and mentioned in passing by Dickens, Twain and HG Wells - the boy, Jaffy, is employed by the animal trader after he saves him from the tiger. Before long, Jaffy is setting sail on a whale ship for the Dutch East Indies to find a "dragon" that will bring Jamrach fame - but nothing goes to plan.
"It is wonderful once you embark upon something like this," Birch says with a smile. "You suddenly become aware of all this great seafaring literature such as The Odyssey and Moby-Dick. The idea of a ship on a voyage of discovery is something of an icon in fiction because it's an enclosed little world. It's a gift for a writer, in all honesty."
Although, back on dry land, there are the requisite bawdy ladies in fetid London streets, Birch doesn't romanticise the cliché of Victorian squalor. The sections on board the Lysander, too, feel visceral and primal. Her depiction of seasickness is stomach-churningly real, and though this is very much an adventure story, the writing is thoughtful and elevating as well as effortlessly readable. I wonder how she summoned such images of wild, untameable seas and filthy, feral streets from her home in quiet, picturesque Lancaster.
"Well, you use your own experience," she says. "I've been on horrible ferry journeys where I can remember thinking 'I could just jump over the side and it would all stop'. For a second, it's almost a possibility because it's such a horrible feeling. So you amplify your own experience for a book.
"But I do love the research, too. I think we all feel we know Victorian London - because of Charles Dickens, probably - so we're used to walking about this fascinating city with all these different nationalities and peoples. It's a terrific time to get lost in because everything was being discovered. We don't have that feeling so much any more. I think we're a bit boring these days, really."
Birch transfers that passion for history to the page - her last book, Scapegallows, was based on the 18th-century adventuress and criminal Margaret Catchpole - without ever being slavish to the biographical facts. It's a tricky balancing act to pull off, and Birch manages it with vivid style, yet it's only in her last few books that she has even attempted historical fiction. Her early work is very different, concerned with the minutiae of everyday life. What changed?
"There was a definite point where I realised I could go wherever I wanted to with my writing, and that's been very liberating," she says. "I realised I could write about things I hadn't actually seen myself - although, that's also very frightening, too. When I wrote The Naming of Eliza Quinn, which is in part about the Irish potato famine, I was worried that the Irish would think an English writer shouldn't be writing about this stuff. It's still quite an emotive topic. But it went down really well, which was such a relief."
It's interesting that Birch should be concerned about a reaction to a particular book because she gives the impression of someone who writes very much for herself. Not in a selfish way, but when I ask whether she intended Jamrach's Menagerie to be an exploration of the human spirit, she looks, for a moment, just a little perplexed.
"There have already been readings of the book pointed out to me, by people who are very ideas-bound," she says. "But I'm not quite sure whether they relate to my experience of writing it. I had the story and the characters at the beginning, not an idea of what I wanted to say. I didn't start off thinking, 'right, a novel about man and nature'. Or, 'I must explore the human spirit in adversity.' I don't want it to be that neat - I quite like the sense that the book was quite instinctive. There was the tiger, the voyage, the terrible situation. That's it, really."
Still, if people are talking about Jamrach's Menagerie's wider relevance, surely that's a good thing.
"Oh yes, of course. I don't mean that I don't want people to take things from Jamrach's Menagerie, that it's just a throwaway book. It's just that I'm not very good at putting out these messages in a nutshell. I just want people to feel for these two childhood friends in the way I did, to go to the brink with them like I did. There is something very beautiful when people come through these awful experiences, and pass something on. Their experiences have to mean something."