Jamie Demetriou on his new role in The Afterparty, playing people with "verbal diarrhoea" and the future of Stath Lets Flats

"I was so sure I wasn't going to get it that I may as well have flushed my laptop down the toilet," Demetriou says over Zoom from his Hackney flat. "The only thing stopping me was the size of my toilet and the size of my laptop."

Arriving on the relatively new streaming platform towards the end of this month, the comedy follows a group of 30-year-olds whose high school reunion ends in tragedy when their former classmate Xavier – a nerd who grew up to be an internationally famous popstar – is found dead at his own afterparty. Each episode is told from a different perspective, with the cast including huge names like 21 Jump Street's Dave Franco, Girls Trip star Tiffany Haddish, Parks and Recreation's Ben Schwartz, Veep's Sam Richardson, Suicide Squad's Ike Barinholtz and Broad City's Ilana Glazer to name just a few.

"You have a dream team in your head of people currently working that you'd like to work with and that was an in-my-wildest-dreams kind of list," Demetriou continues. "And then I got the part and I couldn't believe my ears, eyes, head, whole body, and then they listed the cast to me and I was like, 'How dare you! What are you talking about?'"

Sat in dark yellow jumper and a black beanie, the Stath Lets Flats star bears hardly any similarities to the character he's best known for – the incompetent, verbally-challenged yet well-meaning Stath – although whilst listening to Demetriou speak, you can certainly recognise the silly sense of humour that made the show so popular. His talent for playing socially-awkward, accident-prone losers is definitely utilised in The Afterparty, in which he stars as Walt – a sweet yet under-confident member of the group who is constantly ignored and forgotten about by his fellow ex-students.

"I tend to play people with verbal diarrhoea and it was quite exciting, the challenge of playing someone [who] when they do talk, they don't know what to do to maintain a conversation. It's just a fun comedy game to play.

"And I believe Chris Miller had seen Stath before and... I think [The Afterparty] is an interesting filter to put the thing that I usually like to do through. I guess it's not traditional that someone would read a script and go, 'Oh, that person has the least lines in every episode. I'll be that,' but I was like, 'Oh, I think I'd know what to do there.'"

The biggest challenge Demetriou found in taking on the role was maintaining an American accent throughout. "Ultimately, it is very, very difficult to improvise in an accent that is so new to you. It was a challenge that I really wanted to go ahead with.

"I've done American accents in things but usually only for bit parts and stuff. A full series of one accent – it's beneficial to me that he didn't say too much. It's an undertaking because of the amount of stigma that comes with the job of being a Brit and doing an American accent.

"As soon as you do it – and I can only speak for myself here – but I would imagine any Brit who's seen me do my own voice or one of my British accents, it would become incredibly distracting and just become like, 'Well, all I'm doing is thinking about whether or not his accent is good,' – because that's definitely what I'm doing when I watch it back," he laughs.

While Demetriou auditioned in an American accent and got the role, he still did a few dialect training sessions before filming. "I was very nervous about it. But ultimately, it was the least hostile environment I've ever been in. It was truly like the dream set to be in whilst in the midst of arguably one of the worst global periods of one's life."

Having spent the majority of his acting career on British sets, filming comedies and sitcoms, The Afterparty was one of the few times Demetriou was surrounded by people he only knew "from TV" – and over time, he says he's learnt to "repress" the urge to feel starstruck.

"It's so important to me to not come across as starstruck in order to make the people I'm talking to not feel uncomfortable. I think that it's kind of luckily left my system a little bit – apart from when I meet pop stars," he adds. "If I was to meet any pop star, any kind of X Factor contestant or anyone like that, I don't mind unleashing starstruck hell."

Whilst filming season 3 of Stath Lets Flats, Demetriou was in the makeup trailer, chatting to someone who was playing a potential tenant of Stath's, when he learned that the actor had been in Kingsland Road – a band that competed on The X Factor back in 2013.

"I tried to, you know, hold down how I was feeling about it because he was literally acting in my TV show, but I definitely could have spent a long two-week holiday with him asking him questions about what it was like to be on The X Factor."

On the topic of Stath, fans will remember that the season 3 finale ended on a rather definitive note, with (spoiler alert) Michael and Eagle shutting down, Sophie (played by Jamie's sister Natasia Demetriou) moving to Greece with new boyfriend Al (Al Roberts), her father Vasos (Christos Stergioglou) and his new husband Stephen (Jimmy Roussounis), while Stath reunited with ex Katia (Ellie White) and stayed in the UK to raise baby Dina.

When I ask about the future of the show, Demetriou is reluctant to comment on whether it will definitely be back or not. "I'm really just living in the moment. I've completed a very kind of rocky 14 months of making stuff and I don't feel like it's important to make decisions like that so soon.

"I really want to let things breathe and work out as and when things feel like they're right to do and if inspiration strikes or if it doesn't. I'm not putting a date on anything or a kind of definite decision on anything and that's actually just a truthful answer, I'm not being political.

"I'm really excited to allow my career to go in the direction that feel rights at any given time. I suppose, you know, I have been working on Stath for a decade. It would be good for me to, at the very least, pause. I don't know about putting a full stop, but there's definitely going to be a comma and it just depends on who big that comma is, you know."

He continues: "I mean, it's effectively my whole adult life. Stath as you know it, I've been working on for 10 years. The previous four years, I was doing comedy and doing that voice and stuff, so yeah, it would be good to flex some other muscles."

As for whether there are plans to continue working alongside his sister – What We Do in the Shadows star Natasia Demetriou – the BAFTA winner is sure it'll happen at some point. "It'd be very weird to cut that off and it seems like it's working. I definitely want to act with Tash again.

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"She's making a sketch show with [Stath Lets Flats co-star] Ellie White so I might, if Tash allows me, do a couple of bits and pieces in that," he adds. "Of course I want to work with Tash again. It's been one of the great joys of my life, being able to do that show with her. With how busy she is and how busy I get, the most we get to see each other is when we're working together."

Can we expect him to pop up in What We Do in the Shadows any time soon? "Definitely, if I was offered a part and everything worked out, I would love to be a part of What We Do in the Shadows."

The first three episodes of The Afterparty arrive on Apple TV+ on Friday 28th January, with episodes being released every week from then on. Find out how to sign up for Apple TV+ here.

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