Poisoned chalice: A band of brave authors has taken on the unenviable task of writing sequels to classics such as Winnie-the-Pooh

For the first time in decades I feel the uncertainty that I last felt in my teenage years." The Irish author Eoin Colfer isn't talking about the birth of a new child or the dawn of a new relationship, but rather tackling a book full of characters and ideas that weren't his own.

Even for a seasoned author such as Colfer, taking on the late Douglas Adams' phenomenally successful Hitchhiker's Guide to the Galaxy series – five books that have sold more than 16 million copies worldwide – was not something to be taken lightly. And even now that his And Another Thing..., billed as the sixth book in the series, has been published, it is apparent that Colfer's anxiety has lessened only slightly. "There are still a lot of, almost, threats. As if people are saying, 'This had better be good.'"

Colfer's book joins a list of recent "authorised sequels" to classics, in which some brave authors have written the further adventures of characters from Peter Pan and Dracula to James Bond and Winnie-the-Pooh. And there are more on the way. This week, for example, sees the publication of The Wild Things, by Dave Eggers, to coincide with the eagerly awaited film adaptation of the Maurice Sendak original, Where the Wild Things Are.

It is easy to understand any anxiety over such a seemingly thankless task. These writers are expected not only to get into the mind of the original author, but also, in the same stroke, to take the story on in their own voice. If they fail, they risk invoking the wrath not only of their publishers and the literary estates that have bequeathed them their fictional worlds – and which expect a decent financial return – but also the legions of fans of the originals.

David Benedictus, who first came to the public consciousness in the 1960s with his controversial novels The Fourth of June and You're a Big Boy Now, recently published an addition to one of the best-loved children's series of all time. But when it was announced earlier this year that he would pen the sequel to Winnie-the-Pooh, 80 years after AA Milne and the illustrator EH Shepard first brought Christopher Robin and the little yellow bear to a generation of children, knives came out in the blogosphere. "Shameless, utterly shameless! Reading old copies of Punch and walking in a wood will never make the author into another Milne," sniped one. And those who owned the rights weren't spared the fury: "It's not the bear who has 'very little brain' but rather the Trustees of the Pooh Properties."

Benedictus is surprisingly equivocal in his response to this vitriol – "What's the worst thing that can happen, that I'll be torn apart by wild journalists? Happened before and I survived" – but he does admit that, "At worst everyone will hate me and I'll just crawl under a bush and hide."

No matter what the fans might think, not just anyone is allowed the opportunity to be involved in this sort of project. Just obtaining the literary rights to a novel or a character can be a legal and ethical minefield. Benedictus spent eight years persuading the Milne estate that he was the man for the job, while, for the latest James Bond instalment, Devil May Care, many people needed convincing that the otherwise wildly successful Sebastian Faulks was up to the task. The rights to James Bond belong to the Broccoli family's EON Productions, so permission had to be sought there as well as from the Fleming estate.

"It's a delicate and sensitive situation for someone who controls an estate with such a huge reputation," says Alex Clarke, a commissioning editor at Penguin Books who sanctioned both Faulks' Devil May Care and Colfer's And Another Thing... "Anyone who goes into this kind of project has to have a huge amount of respect for the originator's concept or characters."

So why do writers put themselves through it? Is it more than just a commercial opportunity? "The fact is that these characters are too good, too full of potential to be left alone. If they can be brought back sympathetically, then it's a great thing," says Jon Howells at Waterstone's. "But yes, the books are good for publishers financially as they are proven properties with years, if not decades, of the nation's love behind them. James Bond, Hitchhiker's Guide and Winnie-the-Pooh are some of the best-known franchises in the world, so they do have an advantage."

The benefits of playing off classic novels became clear as long ago as 1966, when Jean Rhys emerged from decades of obscurity and into public prominence when Wide Sargasso Sea, her prequel to Charlotte Brontë's Jane Eyre, became an award-winning triumph. And, as Rhys showed, by basing her novel around the "mad woman in the attic" from Jane Eyre, the central character of a new piece doesn't necessarily have to have been the lead in the original. RN Morris, for example, is about to publish the third in his series of St Petersburg-set detective novels that have taken the shadowy magistrate Porfiry Petrovich from Dostoyevsky's Crime and Punishment and given him a starring role.

While publishers have been maximising the similar potential of Jane Austen's legacy with titles such as Mr Darcy Presents His Bride, there is a quite understandable fear regarding the uncontrollable beast in which this slew of authorised books has its basis: fan fiction. This phenomenon can be traced back to the 1960s, when Star Trek devotees published fanzines such as Spockanalia. But with the internet, the genre has taken off. Sites such as fanfiction.net include millions of stories in dozens of languages. Many take their favourite characters and write new novels around them. Without actively encouraging it, most authors turn a blind eye to what goes on in this new, electronic literary world – but it does have the potential to hamper the sales of officially sanctioned efforts such as Pride and Prejudice and Zombies.

It remains to be seen whether the latest round of updates will be as successful as the last James Bond incarnation. But, if all else fails, readers will still have the originals: "I didn't feel I was doing anything particularly dastardly," concludes Benedictus. "If you're doing a new production of a Shakespeare, you can take great liberties with it – because, in the end, the play will still be there."

The new 'Where the Wild Things Are'

Fleshing out Maurice Sendak's story of Max and his journey to the island where the wild things live, Dave Eggers has created a novel like childhood itself: sometimes weird, sometimes dark, and full of wonder.

Max lives in the suburbs with his divorced mum and older sister, and is assaulted by the stupidity of adults. After a climactic confrontation, he escapes to the island and encounters the huge monsters of the original, now with names, beautifully drawn personalities, and real, volatile, dangerous power.

Max becomes their king but it is a precarious throne, his subjects ready to eat him the moment the rumpus stops being fun.

Like the original, this is far from the cosy world kids are often fed, but it has real heart – Eggers using simple but superbly effective prose to suggest that childhood has to be lived without cosseting for us to grow up with any semblance of a normal personality.

Doug Johnstone

'The Wild Things', by Dave Eggers, is out on Thursday (Hamish Hamilton, £14.99)

The new 'Hitchhiker's Guide to the Galaxy'

At times, reading And Another Thing... is like having Douglas Adams back with us. This sixth book in the Hitchhiker's series is similarly chock-full of fanciful, inventive one-liners and asides, brimming with a burning sense of the ridiculousness of life in the face of galactic indifference.

Occasionally, Eoin Colfer tries too hard at the daft stuff at the expense of emotional engagement, but on the whole this should keep the fan hordes happy.

Once more, the Earth faces imminent destruction, in a plot that takes Arthur Dent, Ford Prefect, Trillian, her daughter Random and Zaphod Beeblebrox into adventures with immortals, gods, dark matter, the viciously bureaucratic Vogons, a fake-Irish property developer and a really large slice of cheese.

The plot isn't all that convincing, but in an imaginative romp to the end of the universe and back, Colfer makes the ride worthwhile.

Aidan Gilchrist

'And Another Thing...' is out now (Michael Joseph, £18.99)

The new 'Winnie-the-Pooh'

There may be no AA Milne or EH Shepard, but thankfully in David Benedictus's further adventures of Pooh, neither is there any red T-shirt, purple Eeyore or any of the other travesties that Disney wrought upon the clan.

Rather, what we get in Return to the Hundred Acre Wood is a delightful chance to revisit some Very Old Friends – as well as Lottie the pearl-wearing Otter, a new character who pops up, one can't help feel, to soothe any qualms about the forest's gender imbalance. All else is as it was: Tigger is as bouncy as ever, Pooh as obsessed with honey, and Eeyore as gloomy.

If there is one criticism to be had, it is that this reads a little too much like it was written in the Noughties: there is fear of a honey shortage after the bees mysteriously disappear. But these are mere quibbles when Benedictus has clearly done a Very Good Thing in reuniting Pooh with his friends.

Susie Mesure

'Return to the Hundred Acre Wood' is out now (Egmont, £12.99)