It was the last day of Edinburgh Fringe Festival where he was performing in the improvised comedy show BattleActs! for the third year in a row, and he was trying to buy some drinks at the bar. But far from ruing the loss of the round, he was jubilant. “It’s the happiest card decline I’ve ever had,” he says, “because I remember just knowing […] that I was going to be in a show that I really loved.” You see, earlier that day, he was told he had been cast in Stath Lets Flats.

He had auditioned in early August having seen the original Comedy Blap on Channel 4, which he says he loved so much that when he and creator Jamie Demetriou first met at a party in 2015, he was quoting his favorite lines to him.

Not that flattery won him the part. He wouldn’t see Demetriou again until the show began filming. The producer had, however, seen him in one of the many YouTube series he had starred in: Nathan Bryon’s Reality. “Around that period was when things started to change and I guess it was a byproduct of all the work that I had been doing beforehand, and people actually starting to see it and share it.”

It was clearly his year, as the director of Stath, Tom Kingsley, then went on to cast him in Ghosts, the much loved sitcom from the Horrible Histories troupe about a married couple pestered by the ghostly inhabitants of their stately home.

After a chemistry test – which Smith-Bynoe likens to “speed dating” – he was cast alongside Charlotte Ritchie as the husband, Mike, to her wife Alison. It’s their easy chemistry that lends the marriage a lived-in feel, and he has a theory as to why it came so naturally. “There's something about being in the same year at school. I hadn’t realized how bonding that is.”

Series four has wrapped and should be coming out in September. And although he is tight-lipped on the goings on at Button House, he hints at some long overdue marital strife. “We forget sometimes that there’s a marriage at the heart of the show. What they’ve taken on is huge […] so there’s a lot that weighs down on the relationship, and I think it's explored a lot more this time around.”

Such starring roles were a long time coming, as he got his first job out of drama school in ITV’s Whitechapel back in 2012. “I was like, ‘I've made it, this is it!’ And then a week later I was back in a call centre and didn't work again for like 14 months.”

He had an agent and was auditioning, but he turned to YouTube to expand his reach, featuring on the Don’t Jealous Me and Humza Productions channels as well as Kayode Ewumi’s viral Hood Documentary.

Smith-Bynoe first met Ewumi when he played his father at a table read for a friend’s script. A few months later he stumbled across his Vines, including those featuring a certain recurring character, the hilariously deluded, aspiring grime MC Roll Safe (R.S), now immortalized in a global meme template. When Ewumi put out the first episode of Hood Documentary, ‘Introducing R.S’, in 2015, Smith-Bynoe got in touch to sing his praises and wound up playing a part in episode two. “And from then on we haven't stopped working together,” he says.

Hood Documentary was picked up for a series by BBC Three in 2016 and so too was the duo’s Elephant and Castle-set comedy, Enterprice in 2018. Now they have their very own Comedy Blap, which has become quite the rite of passage for UK comedy talent, breeding several hit series commissions including Stath, We Are Lady Parts and Pixels. Although Smith-Bynoe says it took all of five years to come to fruition, during which time: “Kayode moved to Ghana and became a pastor, and also got married, and I… got an air fryer.”

Made on a budget of “about £4.60”, their Blap, Red Flag, is a pilot of short, surreal, unrelated sketches starring Smith-Bynoe as a vast array of wacky characters.

He notes the resurgence of sketch, namechecking BBC Three’s Lazy Susan and the upcoming Ellie and Natasia, but whereas those “can have elements of social commentary or touch on subject matter that is quite Zeitgeisty […], the aim of mine was not to touch on any of that, and just to be complete random silliness.”

Not that he thinks silliness is at all lacking in recent TV: “Ghosts is very silly. And Stath is the silliest show that exists.”

However, having been typecast somewhat, he has generally found himself playing comic foils for the zanier characters around him. Dean in Stath is downbeat and disillusioned with his inane colleagues at the letting agency, and Mike in Ghosts plays patient husband to Alison’s far too accommodating spiritual medium. The latter is all the more impressive given that, unlike his wife, Mike cannot see dead people, which means Smith-Bynoe has to literally ignore the nine cartoonish ‘phantoms’ running riot around him.

Does he find the pigeonholing frustrating? “I guess you could say frustrated, yeah. I think that’s why I started writing to be honest. I wanted to show my range.” Especially, he admits, once Ghosts came out. “It started to be less like ‘Kiell’ and more like ‘the guy from Ghosts’, and as much as I love the show and love the character, it’s not what I want to be known as forever.”

What better vehicle to show range than a sketch show, then. In Red Flag he plays all of conga enthusiasts, overeager magicians and panicky thespians, some conjured by him and Ewumi, others by writers they admired.

It was actually Demetriou who wrote one of the most outlandish parts: Harris in the sketch Always Get ‘Em Talking, who launches into an extremely loud and long-winded apology for not staying in touch with a friend, only for us to find out that they have never even met. All the while his actual friend is sat opposite, but Harris just wanted to “get ‘em talking.”

One thing's for sure: Kiell Smith-Bynoe’s got us talking.