The normally tranquil landscape and empty, echoing farm buildings at Luton Hoo estate in Bedfordshire are busily being transformed into the cacophonous world of Dickens’s London. We’re on set for the BBC’s new serial version of Oliver Twist, and an army of carpenters and set designers are creating a gin palace and a subterranean lair to be inhabited by Bill Sikes and Nancy. Tomorrow they start work on a cobbled courtyard that will metamorphose into a tumultuous, screeching, market place. Fagin’s den is being flamboyantly dressed to its distempered rafters.

The famous workhouse scenes, featuring gruel-clutching orphans, have already been filmed in London in an old underground prison that used to take the overflow from Newgate. Here sepia-tinted drabness was the order of the day. “But now we’re creating the hugely seductive and colourful world that Oliver comes to in London after leaving the workhouse,” explains the producer Sarah Brown. “He comes into Fagin’s den and it’s the most warmth he’s ever known in his life.”

The den has a faded velveteen covered bed for Fagin himself and higgledy-piggledy bunks for the 12 lost boys who form his pickpocket gang. The motley crew, aged 10 to 13, are in the make-up lorry now having snot applied to their noses, scabs to their mouths, grime to their nails, faces and limbs. Costume-makers have been burning the midnight oil ripping holes into their threadbare costumes, darning on patches.

“We’ve gone for faded, grubby jewel colours, both in Fagin’s costumes and in those of the boys,” says the award-winning costume designer, Amy Roberts. “Some of the clothes look too big on them, some too small. Often they wear layers of waistcoats and scarves that they’ve stolen on the streets. It’s an eccentric, flamboyantly colourful look.”

The Artful Dodger’s costume has received Roberts’s most particular attention. Adam Arnold, 12, who plays him, describes his garb: “I have this fabulous faded peacock blue frock coat and a beautiful top hat. I’m wearing three layers beneath the coat – one shirt and two waistcoats, plus a neck scarf. I had these fantastic trousers with their holes and patches tailor-made for me. When I get the whole lot on I do feel incredibly, sort of ‘Dodgery’. ”

Haunted as any new production must be by history and the (some might say) definitive casting of the angelic John Howard Davies as Oliver in David Lean’s 1948 adaptation and the cor-blimey wonderfulness of Jack Wild’s Dodger in Lionel Bart’s 1968 musical Oliver!, the producers were determined to find two actors who, despite their youth, could make their own mark. Around 700 boys were auditioned. “These roles are iconic and come with a big responsibility,” says Brown. “Because of other versions every one has an idea in their mind of how they ought to look. We had to forget that and go with our own instincts.”

Arnold, who has been acting since he was 9, was invited to audition after being spotted in the play My Child at the Royal Court. Though he has also appeared in adverts, this is his first TV role. On the other hand, the 11-year-old William Miller, who plays Oliver, had already earned his TV spurs in the historical drama Krakatoa: The Last Years in 2006, which was directed by his father, Sam Miller.

Miller, she says, was more or less a shoo-in for the role from the moment he arrived early in the casting. “We saw many others, but we always returned to him. He has this incredible quality to him and a life going on behind these fantastic eyes. He brings a kind of depth to Oliver that I haven’t seen before.”

Brown says the producers were drawn to Arnold because he was able to bring an emotional complexity to the role that other performances have lacked. “The character has incredible front and bravado, but is still a child and must also have vulnerability. We saw Adam who is just a brilliant little actor. He has all the swagger and chat already in his personality but there is also this emotional dimension to his performance that will make people engage with him and care about his fate. You have to feel for him as well as enjoying his company.”

The writer Sarah Phelps, who has been brought in to adapt Dickens’s best-loved and most adapted novel, saw the characterisation of Oliver as central to the important job of making this adaptation her own. “Apart from the famous musical version I hadn’t seen any other adaptations and I thought it was a bad idea to look at them now because I wanted to do an adaptation of the book, not of the other adaptations,” she says.

“To be honest with you, when I went back to the book I found the character of Oliver overly sentimental, always mithering around and praying to the angels. He was just a little wet for my taste.

“So in my adaptation I’ve done an Oliver who’s a gutsy little lad and stands up for what he believes in, even when he’s terrified. We cheer him on because we know that in his heart he’s a good and brave boy, and William Miller has been able to convey all of this superbly.”

The choice of Phelps as the adapter is almost a mission statement. She is normally on the writing team of EastEnders and this is her first adaptation of a classic novel. But, as in the BBC’s groundbreaking adaptation of Bleak House, the aim is to give the story an episodic, populist feel. “We wanted a drama that would have resonance even to people who had never picked up a piece of classical literature in their lives,” says Brown.

By choosing Phelps, of course, the BBC also hope to make this version the most gritty and modern of all the Oliver Twistadaptations. “What working in soap teaches you is never to wiffle-waffle around the edges of a story, but to get straight in up to your elbows. And that is exactly what I have tried to do here.”

Those then expecting the kind of food-glorious-food larks of Oliver! the musical will be disappointed. This serial version (to be shown as a one-hour episode followed by five half-hour slots) will be far darker – Walford meets the workhouse.

Fagin also constitutes a departure, both from Alec Guinness’s hook-nosed miser in Lean’s adaptation, and from the character in the book itself. “Dickens always refers to Fagin’ as ‘a vile and withered Jew’,” says Phelps. “I wanted to create a much more complex Fagin. Yes he wears a yarmulke and doesn’t eat pig and keeps the faith. But he is not defined, as in other versions, by being a Jew.”

Expect, then, a far more nuanced performance from Timothy Spall, who brought his own passion for Dickens to the role. “Tim and I talked about the look of Fagin,” says Amy Roberts, “and his comments were invaluable. He said: ‘The central thing about him is that he’s a sensualist. He loves beautiful things. He’s a magpie.’ So we dress him in all these fabulous but faded silks and velvets.”

Phelps admits that liberties have been taken with the original book – that it is not, perhaps, the most faithful of all the versions. For example, in this adaptation Nancy is played by a black actress, Sophie Okonedo. In Dickens’s novel, and in every other take on Oliver Twist, she is white. “But, from the start, I saw Sophie’s face when I wrote the part. And I wanted that character to reflect that Dickens’s London was as multicultural as ours.

“I also wanted [viewers] to feel that even though this is a classic story set in the 19th century, it has echoes in the modern world. We hear about feral gangs of boys in hoodies, nicking mobile phones. Really they’re just our modern version of Fagin’s boys.”

In other ways, Phelps has been more of a Dickens purist than other adapters. Her version of the central relationship between Bill Sikes, played by Tom Hardy, and Nancy, is far closer to the book’s. Hardy explains: “In previous versions, there has been a kind of hamminess to Sikes. He has been played as a towering rock of emotionless violence.

“Oliver Reed’s portrayal, magnificent as it was, showed him as a Neanderthal beast, and you did wonder what Nancy was doing with him.

“In Sarah’s script she sees much more tenderness in the relationship. In the end, he kills Nancy, but he is haunted to his own grave by her death. Don’t get me wrong; I’m not playing him crying over kittens. Sikes is still a turd that’s managed to float to the top of a s*** pile that the Dickensian underworld represents.”

What the makers hope is that the audience will almost be able to smell Dickens’s flamboyant yet squalid London. But despite her confidence in the project, Brown accepts that she is bound to be asked: “Why do we need another Oliver Twist?”

“I’d say watch it and then tell me there wasn’t another great, modern version to be done,” she says. “There was. And this is it.”

Oliver Twist begins Tues Dec 18, BBC One, 8pm; Sophie Okonedo is interviewed in today’s Magazine

Where are they now?

John Howard Davies (Oliver in David’s Lean’s 1948 film) became the BBC’s head of comedy from 1977 to 1982.

Anthony Newley (Lean’s Artful Dodger) had a varied career as an actor, composer, Joan Collins husband and singer of seven hits.

Mark Lester (Lionel Bart’s singing Oliver in 1968) now works as an osteopath.

Jack Wild (Bart’s Dodger) lived it up as a pop singer and children’s TV star before alcoholism and ultimately cancer claimed him. Elijah Wood (Dodger in 1997) went on to conquer Mordor, and the world, as Frodo Baggins.

Sam Smith (Alan Bleasdale’s star in 1999) has vanished from view.

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