Secrecy around the new series of Broadchurch was so intense producers used code names for the show, its stars and its writer and scripts were digital and password protected, with personalised watermarks emblazoned across each page, it has been revealed.
The crime drama will return to ITV later this month for a new case, which sees the detectives played by David Tennant and Olivia Colman investigate a sexual assault in the close-knit community.
Former Coronation Street actress Julie Hesmondhalgh and Sarah Parish, known for appearing in Cutting It and Doctor Who, have joined the cast for the show's final outing and Parish said keeping secrets was of the utmost importance.
She said: "All scripts have a code name and there is a different writer's name. Our names are printed throughout the script and often the top actors have code names too, so people don't come to the set."
The identity of the attacker was kept from the cast until late in the filming process and creator Chris Chibnall did not write the ending until after production had started.
Producer Dan Winch said: "One thing we do to help Chris is we don't necessarily reveal certain elements up front to allow Chris to be inspired and to keep evolving with the writing of the full series as we go, rather than write all eight episodes up front.
"Chris has got an end point we know we are working towards but the majority of people aren't in that bubble, which has maintained that fantastic sense of a real buzz.
"It's one big game of Cluedo but done with sensitivity to the characters we have explored and come to know and love."
He added: "We send out scripts on email and everyone has a unique password. I'm so paranoid I will leave my hard copy script around I shred them after script meetings so I just have them on digital.
"Everything is watermarked and the sides each day have your name on them, but we have had some near misses where people have left them lying around by accident.
"We had someone who went on holiday and their laptop got stolen somewhere in Europe and we had to shut down and change the email addresses for that person.
"We take everything really seriously and for the right reasons to make sure for that launch we won't have given away anything that will ruin the journey.
"All the scenes that have involved quite dark, quite sensitive emotional content, it wouldn't be appropriate for those pages to be flying around at the farm shop we have been at on various occasions, so we are just careful and make sure we do everything we can possibly do to maintain that secrecy and suspense."
Broadchurch will return to ITV on February 27 at 9pm.