In order to maintain secrecy both on and off set, the cover page of each script featured a code name while creator Chris Chibnall used a pseudonym.
Speaking to press, including Express.co.uk, at a screening for the first episode of Broadchurch, Chris admitted that his nom de plume was Phyllis Whitby – a combination of his grandmother's first name and his middle school.
When asked what the programme makers had kept secret during filming, Chris said: “A lot, we write very little down. Every outline – we have code names. The names on the script aren’t even Broadchurch.
Broadchurch used 'Downton Abbey' style names to stop script leaks
We start by lying on our cover page and we sort of go on from there.
“On season two and season three the script title pages – my name isn’t on them. I did write them. They are 'the Downton name’.
He continued: “The reason behind that is because people leave scripts lying around.
“We start by lying on our cover page and we sort of go on from there. We watermark everything, everything is password protected.”
Chris added: “There’s a lot we do and we don’t issue parts of certain scripts and we film alternate versions and we do all the things you’d expect we do."
However, he would not be drawn on whether alternative endings had been filmed for season three.
The cast and crew were also issued with password-protected scripts to ensure an extra layer of security during the shoot.
Broadchurch is well-known for its secrecy, during filming on season one the cast only discovered the day before shooting the final episode the identity of the killer.
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Season three will return to the tight-knit coastal community, rocked once again by a brutal crime
Meanwhile, one actor was forced to travel in disguise to and from set while working on season two so that fans would not realise he was still part of the show.
It seems that the cast are just as much in the dark for the third and final outing this year.
Julie Hesmondhalgh, who plays sexual assault victim Trish, said that she and her co-stars would spend each morning trying to guess who the perpetrator was.
"None of us knew and I think it’s a really good indication of the whodunit element. It’s a bit crass to say but it is a thriller. All of us, every morning in make-up we were thinking up outlandish theories, everyone of us," she said.
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David Tennant and Olivia Colman will return for season three
Season three will return to the tight-knit coastal community, which is once again rocked by a brutal crime.
David Tennant and Olivia Colman will be reprising their roles as police officers Alec Hardy and Ellie Miller respectively.
Arthur Darvill, Jodie Whittaker and Andrew Buchan will also be returning, while Sir Lenny Henry, Sarah Parish, Georgina Campbell and Mark Bazeley will be joining.
Broadchurch season 3 will air on ITV later this year.