Will Sharpe has only been surfing a couple of times, but he really loved it. “So I’m not a surfer, I’m not very good at it, I’ve been twice,” clarifies the 35-year-old English-Japanese actor, writer and director. “But there’s something about being in this huge, loud, ‘other’ force and I never feel calmer than when I’m underwater in the sea. I just really took to it.”

Sharpe sees parallels with his work, which has so far included the surreal, darkly funny sitcom Flowers starring Julian Barratt and Olivia Colman that he created for Channel 4, and a magnetic performance as sarcastic, self-destructive Rodney in the BBC drama Giri/Haji, which earned him a Bafta in 2020 for best supporting actor. “When I came back to writing, having been surfing, I found myself reflecting on how there are certain similarities: you have to get everything technically right, but you’re still at the mercy of this much greater power,” he says. “And how 95% of the time you are getting the shit kicked out of you, but the 5% of the time that it works, it’s so exhilarating you just want to do it again straight away.”

Career-wise, Sharpe has just caught a couple of epic waves. First up is Landscapers, a four-part drama that he has co-written and directed for HBO and Sky. It features Colman, again, and David Thewlis as Susan and Christopher Edwards, a seemingly ordinary couple who in 2014 were convicted of killing Susan’s parents 16 years earlier and burying them in the back garden of their Mansfield home. Then, in the new year, he has the feature film The Electrical Life of Louis Wain, starring Benedict Cumberbatch and Claire Foy, which he co-wrote and directed. Also inspired by a true story, it recounts the life of a chaotic British artist who became renowned in the late 19th century for his whimsical, sometimes psychedelic drawings of cats.

To describe Sharpe as a singular and precocious talent would be understating what an original and empathic vision he brings to these projects. The star power he can call on – both Colman and Cumberbatch picked him out specifically – is one indication. I ask Colman why she was so keen to enlist Sharpe for Landscapers. “Because I had loved working with Will on Flowers. He has the most wonderfully creative mind, and as a director I loved the notes he gave me,” she says. The American director Paul Thomas Anderson has said that he considers Flowers “fully formed” and “perfect”.

Nick Cave, a collector of Louis Wain’s work who has a cameo as the writer HG Wells in The Electrical Life…, has noted: “It is a beautiful, heartfelt hallucination of a film about a most singular and extraordinary man. I highly recommend it.”

In person, Sharpe, whose face is half-hidden by a Beatles mop of black tousled hair, is more modest and reticent than you might expect from these raves. “I’m socially pretty uncomfortable,” he says, over a coffee in a cafe in east London. “Or at least I think I am.”

Sharpe traces this shyness in part to his upbringing. His mother is Japanese, and until the age of eight he lived mostly in Tokyo. His family then moved to Surrey, when his father, who now works for the Financial Conduct Authority, took up a new job. “If you’re mixed-race, when you’re in Japan you feel British, and when you’re in England you feel Japanese,” he says. “You’re trying to get your feet on the ground wherever you go. I definitely found it took some adjustment moving to England from Japan, and I think that has given me perhaps an outsider’s perspective on here. In the same way that I have an outsider’s perspective on there.”

For someone with a degree of social awkwardness, a career in performance might not seem an obvious move. But as a child, Sharpe liked Japanese sketch shows and Mr Bean; he then played in bands (keyboards, guitar) as a teenager and would become president of Footlights at Cambridge, where he studied classics. After graduating, he went to London and tried to book standup gigs.

What was his act? “I can’t really remember now,” Sharpe says, dubiously, before laughing at a salvaged memory. “Sometimes I’d be so nervous I would do it in an American accent. I guess it felt like safety or something because I wasn’t fully myself. I just like the feeling of trying things out. And in a funny way, even the times where it doesn’t go well, when there’s four people in a room and virtually no response, that felt motivating as well in a different way. It was a fun but strange time.”

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Perhaps because of that outsider standpoint, Sharpe’s output as a director is defiantly and excitingly non-derivative. Nick Cave is not the first to note the hallucinatory quality to his work. This is especially evident in The Electrical Life of Louis Wain, which Sharpe co-wrote with Simon Stephenson (Paddington 2), based upon a story by Stephenson. What could have been a by-numbers biopic is rendered stranger, more fun but also deeply affecting. It’s not a spoiler to say that Wain wound up penniless and in Bedlam psychiatric hospital, but Sharpe’s film imbues his life with a posthumous dignity.

Making The Electrical Life… felt like “a big step up” for Sharpe. He had not heard of the artist when he was approached by Cumberbatch’s production company, but was quickly won over. “I found him to be a very inspiring and heroic figure – he showed huge resilience in the face of countless challenges,” says Sharpe. “So I just fell in love with him.”

Working with Cumberbatch – “he has this extraordinary stamina and he can always bring it” – turned out to be easier than herding Wain’s subjects. “Filming with cats, at times they give you spontaneous magic,” says Sharpe. “And often they behave like cats and do whatever they want and you just have to adapt.”

His other big new project, Landscapers, came about after the American director Alexander Payne dropped out because of a scheduling conflict. The bones of the story could have made for a fairly conventional true-crime procedural: were the Edwardses really responsible for the death of Susan’s parents? How did they hide in plain sight for so long? Sharpe, though, pushed to go deeper; there is a dream-like, fantastical element to his retelling of events. One of the incongruities of the case was that Christopher and Susan Edwards were obsessed with Hollywood memorabilia, spending a six-figure sum on posters, photos and letters; when they finally handed themselves in to the police, their personal effects included handwritten notes from the actor Gérard Depardieu.

“They’re both projects where the central characters are people who are difficult to understand, or who maybe didn’t quite sit in the world in as straightforward a way as they could have done,” says Sharpe. “I wanted to understand these people. I knew I could never fully achieve that, but I wanted to try as best as possible to get into their headspace.”

Sharpe does not appear himself in Landscapers or The Electrical Life of Louis Wain, but believes that switching between acting and directing improves both disciplines. “I sometimes use the analogy that if you’re driving a car, but you’ve recently ridden a bicycle, then you have a greater sense of how it feels for the others,” he says.

As for what he does next, Sharpe’s not sure. When we meet, in early November, his partner, the Loki actor Sophia Di Martino, is expecting their second child any day. He smiles and notes that that might preoccupy him for a while. But he is feeling the pull of acting again, and also wants to write something of his own from scratch.

Colman seems convinced that with Sharpe we are witnessing the formative stages of a great creative talent: equally skilled as an actor, writer and director, and still just in his mid-30s. “All of those things should make me dislike him – it’s deeply unfair,” says Colman. “If he turned up playing some sort of sport for England, I wouldn’t be surprised. And it’ll be a sport he never even tried before.”

Maybe we shouldn’t rule out Sharpe ending up as a surfer just yet.

• Landscapers is on Sky Atlantic from 7 December

• The Electrical Life of Louis Wain opens in UK cinemas on New Year’s Day