Watching Sky's new thriller The Third Day, you might assume that its setting – a remote, uncanny island reachable only via a winding causeway that emerges from beneath the waves – is... well... some kind of unlikely invention. Surely this must have been filmed using multiple locations, plus a heavy dose of CGI?
But no! You would be wrong. Because the drama was filmed on a real-life island which even shares a name with the sinister, creepier version we see on screen: Osea Island.
The real Osea Island is located in the estuary of the River Blackwater in Essex, to the East of England. This tidal island is only 1.5 km squared, and is connected to the riverbank just twice a day for four hours.
As for inhabitants, if you go there you won't find Mr Martin (Paddy Considine) and Mrs Martin (Emily Watson) running a Hotel California-style pub. (You can check out any time you like, but you can never leave.)
But you might bump into music producer Nigel Frieda, who owns the entire island; Frieda is known for his work with the Sugababes and The Rolling Stones.
The Third Day star Katherine Waterston told RadioTimes.com and other press: "My understanding is it's a privately-owned island, and the owner was familiar with Punchdrunk, and he was so excited to be part of creating this, and really seemed to get what we were doing and that it was rather special. So I think they were happy to have it there.
"But there aren't many inhabitants. There are some people that live there to maintain the buildings, or that work for the owner of the island, but we didn't really see people too much when we were there, except for our own crew – who really took over the place when we were there!"
The real Osea Island is billed as a great destination for sailing, fishing, cycling, and walking, and is available (in normal non-COVID times, at least) for holidays, corporate events, parties, weddings, festivals and conferences, with "charming cottages, apartments and grand houses" and the option of exclusively hiring the entire island for private events.
There's a 'seafood shack' and a restaurant called 'The Bomb Factory' (so-named because it's in a former First World War torpedo store).
The island's official website tells potential visitors: "With only the stars for streetlights and an absence of traffic and aircraft noise you may sleep deeply and wake up refreshed to the sound of bird song. It’s a place to switch off from a troubled world and savour moments as you wander along its 5 miles of private beaches, rarely bumping into another soul."
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"Filming there was infuriating because of the tide," commented Emily Watson.
"Exactly as in the story, if you missed the tidal causeway, you then had to wait until the tide came in enough, or did whatever enough, to get a boat. There were only certain times of day when you could get on and off the island. Occasionally we’d be fighting as we were supposed to wrap at 8.15pm and the crossing closes at 8.30pm, then they call a few minutes grace where they go over for a bit, so there’s a window of about five minutes for everyone to de-rig, wrap and - if you’re trying to get off the island - to go... hat was a bit hairy.
"But a lot of the time we just stayed the night, there’s a whole set and all those houses and everything were also cottages where people were living. So it was a bit like being at a really weird boarding school as well."
She added: "I did once go home at one in the morning on a speedboat under the moon. It was really quite extreme and weird."
Naomie Harris added: "Osea Island is a place where lots of people go. Cara Delevingne apparently goes and has parties there, Kate Moss is another person who frequents there, they absolutely love this island. And so there’s something bleak about it but there’s also something beautiful about it as well, something earthed and mysterious and I guess people really love that."
Osea Island has actually had a very interesting history since the start of the 20th century, when it was purchased by Frederick Nicholas Charrington. Having broken away from his family's brewing business to become a temperance campaigner, he bought Osea Island for use in treating drug and alcohol addiction.
Then came the First World War, when Osea Island was used as a torpedo boat base and covered with temporary huts for the 2,000 soldiers stationed there. And then in the Second World War it was used by the British Army.
From 2005, harking back to the days of Charrington, it again became a rehab centre for those suffering from addiction. But The Causeway Retreat, whose patients had included Amy Winehouse, was closed down in 2010. More recently, Osea Island has become a destination for musicians – with its own fully-equipped recording studio available to hire at the Manor House, as well as accommodation for more than 100 people.
As the recording studio's website puts it: "Private, luxurious and genuinely beautiful, Osea Island is the UK's leading retreat for the music industry. Only an hour and a half drive from London, it is located in the magnificent Blackwater Estuary off the coast of Essex. Osea Island is a blank canvas that can be the backdrop for any number of musical activities, from writing to recording to parties and much more."
While the majority of The Third day was filmed on Osea Island, the production team did also make use of a few other locations.
Waterson explained that in the TV show, "we have a much more sort of diverse landscape than what the island actually offers, so we went to forest in Kent; it was an incredible tour of Southern England for me, national parks that I didn't know existed."
The Third Day airs on Sky and NOW TV from 15th September 2020. Check out what else is on with our TV Guide.