She’s created literary pilgrimages to Rome, to outback sheep stations, and latterly traced the well-trodden estates of late Georgian era pastoral England, but to visit Colleen McCullough these days, you enter a lift in a nice but unremarkable Pyrmont apartment building close to Sydney’s central business district, which takes you up four flights.

It’s quite a surprise when the lift doors open straight onto the spacious lounge room of a mega-selling author. The bespectacled woman herself, dressed in casual baby blue top and pants and wrapped in a pink scarf, her grey hair cropped no-nonsense short and swept back, steps forward and extends one hand in greeting.

The other hand is leaning against a wooden cabinet as insurance against her failing sight and to stop her self-described “rat shit” 71-year-old body – her problems are “mostly skeletal” – falling over.

The apartment is filled with plump lounges, walls of DVDs and books; she favours historical works and fat airport thrillers. Yet the dust jackets of her own books still say she lives on Norfolk Island with her husband of 25 years, the strapping 190-centimetre Ric Robinson, an exporter of palm seeds to Belgium and Holland.

Why so settled in Sydney? “I’m in exile,” says the author who in her late 30s famously swapped a career as a neuroscientist to write the novels Tim, The Thorn Birds and more recently a long-running series on the likes of Caesar and Antony and Cleopatra.

“It’s purely a temporary measure, because I’m crippled, and I can’t live in our house until we get a lift. Its taken us nearly three years. We finally found a company about six months ago willing to do it. But the lift hasn’t reached Norfolk Island yet.”

She leans back in her seat and erupts in her trademark deep-throated, kookaburra laugh. “Everything happens very slowly there.”

McCullough is not slow in turning out the books; the leaking blood vessels and retina damage inflicted by macular degeneration may have played havoc with her central vision – she no longer draws or paints because she cannot see where the brush or nib touches the surface – but she can still use her trusty typewriter to compose a novel, thanks mostly to peripheral vision.

The deterioration in her sight has slowed, courtesy some ghastly-sounding eye injections.

Born in Wellington in central-west NSW in 1937, her parents always tried to pull Colleen’s nose out of books and remove her from school. She has called her father James, an itinerant cane-cutter who had mistresses, a “bastard and a miser” – he had refused to pay to fly her brother Carl’s body back to Australia when he had a heart attack and died swimming off the island of Crete – while McCullough says her mother Laurie was “bitterly anti-intellectual”.

Her 19th book, The Independence of Miss Mary Bennet, has just been published. It’s a sequel to Jane Austen’s Pride and Prejudice, 20 years hence. She admits it’s the literary equivalent of a chick flick; a “chook book”.

McCullough portrays Mr Darcy as a heartless Tory prime ministerial wannabe, who has trapped a weak Elizabeth in a sexless, loveless marriage. Darcy has virtually imprisoned Elizabeth’s sister Lydia, now a trollop and bag lady who screams “f” and “c” swear words in genteel company.

The star however is another of Elizabeth’s sisters, Mary, who sets out to chronicle the lives of the poor, but instead gets kidnapped by a mentally disturbed, Jesus-loving sect leader, and held prisoner in a series of tunnels.

Mary’s confidantes include Charlie, the 18-year-old son of Elizabeth and Mr Darcy, who is gay; McCullough employs the historically appropriate euphemism “devotee of Socratic love”.

Austen scholars and ardent fans – the “Janeites” – were not amused when fed the the plot lines. McCullough's book “sounds so utterly tawdry and silly that I have no intention of wasting time discussing it with you”, sniffed British Austen scholar Deirdre Le Faye, editor of a collection of Austen’s letters.

Sue Parrill, the Jane Austen Society of North America’s book review editor, warns Darcy is the “ultimate sex object for many readers”, and Austen fans “like happy endings and will not like to see Darcy savaged”.

There are some 1000 published sequels and prequels to Austen’s mere six novels, says Susannah Fullerton, the Paddington-based president of the Jane Austen Society of Australia. But “when I hear Elizabeth Bennet is portrayed as weak, I shudder,” Fullerton says.

“She is one of the strongest, liveliest heroines in literature … [and] Darcy's generosity of spirit and nobility of character make her fall in love with him – why should those essential traits in both of them change in 20 years?”

So is she expecting to be smoked out by critics? McCullough takes a Peter Jackson cigarette from the packet. “Will this drive you mad?” she asks, before lighting up. "They’ve been backlashing me since the year dot, mate,” she thunders.

She explains why, despite always declaring she would never write a Thorn Birds sequel “because I like to break new ground”, she has written a sequel to one of the most re-imagined, regurgitated novels in the English canon.

McCullough says she simply always wondered what happened to Mary. And there’s “no way in a fit that the marriage of Elizabeth and Mr Darcy could have succeeded”, she argues. “He was absolutely rigid and inflexible, and she would poke gentle fun at him to make him see how constipated a person he was.

“If you live with somebody and they poke gentle fun at you day after day, what are you going to feel like? Decking them!”

In the end, plot trumps history: “I didn’t do a lot of research for this book. If there are inaccuracies in it, that doesn’t matter, because the kind of people they were mouthed inaccuracies every day anyway.”

A couple of years ago, Germaine Greer said McCullough’s 1977 bestselling Australian epic The Thorn Birds was “my favourite bad book”, but at least the critics could never mistake McCullough herself for a sentimentalist or romantic. She eschews reading love stories, even if she occasionally writes them.

McCullough says her unhappy childhood did not influence her decision to never have children. “I can’t stand kids; I never could and I never will.” Another raspy laugh. “It’s true! Only their parents could think they were beautiful.”

Of course, she inherited Ric’s two “beautiful” children, now in their 30s, but “they were house-trained”.

Both her parents now being deceased, has she forgiven them? “No, not at all!” she says – but laughs. “Why should I forgive them? All this self-help, love-thy neighbour kind of crap doesn’t turn me on. I figure what they did was unforgivable, and I will never forgive them.”

She’s been outspoken in the past on issues such as underage sex among Pitcairn islanders, and the Janelle Patton murder case on Norfolk Island. Does a journalist lurk behind the fiction writer?

McCullough reveals she has been “squirreling” away non-fiction essays, but for publication “after I’m dead – it will be more fun that way”.

She’s philosophical about her deteriorating health. “I’ve had a good run for my money,” she says. So does she fear anything?

McCullough pauses. “Yes, that my husband should go first. I wouldn’t like that. But aside from that, pretty well I suppose it’s a question of learning that you can cope.”

The Independence of Miss Mary Bennet is published by HarperCollins, $49.99.