Even the actors have no idea how the second series will end. Its creator Chris Chibnall went to great lengths to keep the plot line secret, as Adam Lee-Potter discovered when he met Chris in West Bay, the setting for this gripping thriller

Great British Life: The cast of Boradchurch 2: L-R: Eve Myles, Charlotte Rampling, Marianne Jean-Baptiste, Arthur Darville, Olivia Colman, David Tennant, Phoebe Waller-Bridge, Andrew Buchan, Jodie Whittaker, James Darcy, Carolyn Pickles and Jonathan Bailey © Kudos/ITVThe cast of Boradchurch 2: L-R: Eve Myles, Charlotte Rampling, Marianne Jean-Baptiste, Arthur Darville, Olivia Colman, David Tennant, Phoebe Waller-Bridge, Andrew Buchan, Jodie Whittaker, James Darcy, Carolyn Pickles and Jonathan Bailey © Kudos/ITV (Image: Kudos/ITV)

The second time around, the West Bay whodunnit is murkier, the secrets deeper, the obfuscation total. Even the film set was shrouded in mystery, guarded by two former Coldstream Guards hired to jump on any lurking paparazzi.

Two years ago, one question united the nation: who killed Danny Latimer? The drama was ITV’s most-watched show of the year and generated a record 470,000 tweets – 260,000 of them during the final episode, which was watched by more than 10 million people. Only after eight tortuous weeks did we finally learn the answer to the most taxing puzzler since Kristin shot J.R. 35 years ago.

It was, of course, Joe Miller – the closeted husband of policewoman Ellie, played by the redoubtable Olivia Colman. Or was it? We will have to wait until the final episode to find out for sure. As Joe said in January’s tense opener: “Nobody’s innocent. Everyone’s hiding things.”

There is only one certainty: we’re set for another bumpy, unpredictable ride. And that goes for pretty much everyone, bar Chris Chibnall, the show’s Bridport-based creator - the only person who knows the whole, untrammelled ending.

Even his stars - Colman, David Tennant, Charlotte Rampling et al – have been kept, as much as possible, in the dark.

Chris explains: “First time around, we didn’t think anyone would be interested in it so we were pretty lax about security. This time, we realised we had to lock it down and keep our secrets safe.

“We watermarked all the scripts, individually named them so we could identify any leak and made all of the cast sign non-disclosure agreements. We even hired a couple of former Coldstream Guards to jump in the way of any paparazzi on set. I’ve even kept my old chum David in the dark. I think he was both offended and pleased. I’m not exactly the Alfred Hitchcock of Dorset but that’s certainly how I like to keep my actors.

“If David leaked a script, I wouldn’t work with him again. But I’d be very surprised if he did. There’s a lovely atmosphere on the Broadchurch set and you can’t underestimate the importance of that. It’s great to build something special and then have an audience appreciate it. It doesn’t enrich the viewers’ experience if they know the plot in advance.”

By this point in the interview, the regulars in Chris’ local, West Bay’s Ellipse café, are agog, hanging on his every word from afar. He has become the Elvis of DT6.

Great British Life: Chris Chibnall - photo by Jenny HillChris Chibnall - photo by Jenny Hill (Image: Archant)

Chuckling, he adds: “We’ve been really tight about giving stuff out to the cast but I try to be inclusive. When I hold back scripts, I don’t do it to be annoying. We tell the actors what we’re going to tell them and we tell them what we’re not going to tell them. You want them to know where they’re going but you don’t want them to be foreshadowing things.

“There is a definite ending in series two but we have filmed various options. There is more than one version and we can bend it as we go. With a show like this, you keep your secrets as long as you can. It’s like releasing an animal into the wild.”

Speculation has been frantic, spurred by the occasional leaked picture that has snuck past even Chris’ guards.

But Chris is – as ever - unruffled.

“I’m not worried about secrets leaking or the photographs that have sneaked out. Our big reveals are generally done in studio and we have even done fake shots to put newspapers off the scent.

“It’s slightly irritating because I don’t think the audience wants to know but equally it’s flattering. I think that’s the price you pay if people like the show.”

The second series is recognisably from the same stable as the first but the plot dynamic is – intentionally - very different.

“I didn’t want to come back and just tell the same story in different clothes - another dead body beneath the cliffs and two detectives going ‘Oh my God, it’s happened again, what are the chances?’

“But equally it’s a thriller, it needs to have twists and a propulsive engine. There are still all the ingredients that for me are Broadchurch - big storytelling, lots of emotions, lots of detailed character work and great acting.

Great British Life: Charlotte Rampling as Jocelyn Knight © Kudos/ITVCharlotte Rampling as Jocelyn Knight © Kudos/ITV (Image: Kudos/ITV)

“The second series isn’t necessarily the same kind of Agatha Christie whodunnit but there are still questions that the audience is going to want answers to. There’s mystery, there’s crime, and we still have some of the same characters, along with some new ones.”

Indeed. We may have lost Pauline Quirke but we’ve gained Charlotte Rampling, much to 45-year-old Chris’ obvious delight.

“I so wanted Charlotte,” he says. “I’d written her character and I was watching a documentary about Steve McQueen, the film director, which showed a video installation piece he’d made with Charlotte where he just poked her eye.

“It was one long close-up and she was so mischievous but also tough and steely. I just thought that combination was such a perfect match for how I saw this character.

“I rang the casting directors and said ‘I know it’s crazy but can we just ask Charlotte Rampling?’ They came back almost immediately and said ‘Good news, she’s curious’ and away we went. That is what’s so fantastic about Charlotte – she’s so open to new experiences.”

Chris is – as so many screenwriters are – part-auteur, part-fan.

“I see my cast as a family. When Charlotte joined, everyone thought ‘Oh my goodness’ but David and Olivia were truly thrilled.

“They are so sweet and ungrand and collaborative - I wouldn’t have made this series without them. They’re integral to what I wanted to do and the identity of the show. Frankly, I don’t want anyone else to work with them.

“But Charlotte is extraordinary - she is the least starry actress you will ever meet. She’s so down-to-earth, smart, funny and delightful - the crew all adored her.

Great British Life: Arthur Darvillas Reverend Paul Coates © Kudos/ITVArthur Darvillas Reverend Paul Coates © Kudos/ITV (Image: Kudos/ITV)

“When you’re working with material that’s quite challenging, with dark hinterlands, you want to set up an atmosphere that’s supportive and fun. You need that when what you’re working with is quite difficult.”

Chris goes on: “My 11-year-old son has been begging me but I won’t let him watch this series. It’s too upsetting. It would devastate him. Season one was bad enough - he kept getting hassled at school, with older kids demanding to know who was the killer.

“But this series features the cheekiest cliff-hanger yet – a real shocker. I wanted to keep people on the very edge of their seats.”

Chris has a muscular TV background, having written for Dr Who, Torchwood and Law & Order: UK. But Broadchurch was very much his breakthrough. And he revels in his role in this new golden era for British drama, alongside the likes of Line of Duty, Happy Valley and The Honourable Woman.

“The audience want TV novels and that’s better for character-writing, so you’re more likely to attract good actors – it’s a very rich time. But you’ve still got to serve up cliff-hangers, thrills and twists.”

For all the fanfare, Chris is still sweetly surprised by the furore surrounding his creation.

“I hadn’t anticipated the attention the show would get and I thought locals would be especially irritated. But people here seem to feel a real sense of ownership, which is fabulous and touching.

“But there are never any guarantees. You’re a fool if you think you can take an audience for granted and this is a hard job: it’s difficult to get things written, it’s difficult to get things commissioned and it’s incredibly difficult to get things on air. All these stages mitigate against success.

“And I’m not going to say this series is the best writing I’ve ever done – that would be like a parent saying ‘this is the best child I’ve ever had’. All that matters to me is one question: have I done the best job I could? And that answer is, I think, ‘yes’.”

The West Bay faithful are wandering over thick and fast now, laying siege to our once-quiet corner table in the window. What they all want to know – just halfway through series two – is will there be a third? Such is Broadchurch’s addictive quality.

Chris is polite to a fault, affable and charming. But he’s got a poker face that would fox even Tennant’s DI Alec Hardy.

“It’s not an infinitely returning series,” he says, carefully choosing his words. “I can only say we won’t be doing Broadchurch 9. I want it to be rare and precision-tooled. Right now, I need a holiday.”

Come February 23, so might we. As Chris says: “You’ve still got a lot of dark, emotional trauma ahead of you. Brace yourself for upset and shock.”

Can’t wait!