Winning a BAFTA award is cool, but have you ever had a fart-off with Sir Gary Oldman?

Lenny Rush, the 17-year-old British actor who joined Season 6 of Apple TV’s Slow Horses, has done both. And from the way he gushes about his “unreal” experience on the acclaimed spy thriller, it’s hard to say which achievement he treasures more.

In the show’s stellar sixth season, Rush plays Reece Nesmith, a murder witness who’s on the run with Slough House’s misfit MI-5 agents. As the youngest person the Slow Horses have ever teamed up with, Rush was thrilled to learn that Reece would share Lamb’s (Oldman) penchant for swearing and effortlessly hold his own against him, Roddy Ho (Christopher Chung), and the rest of the unconventional crew.

“It’d be horrible if they brought the kid in and then the show got a little bit more family-friendly. No one wants that,” Rush, who regularly steals scenes with unexpected sass and expert comedic timing, told DECIDER over Zoom. “The writers could have had a kid that didn’t speak much. He could just be there. But they made quite a bit out of the character. I’m very pleased.”

In celebration of Rush’s fan-favorite Slow Horses character, he spoke with DECIDER about Reece and Lamb’s fart-off, crafting hilarious tension with Chung, Episode 4’s Shake Shack showdown with Hugo Weaving’s Frank Harkness, and more.

DECIDER: You not only joined Slow Horses six seasons in, but you’re also the youngest person the team has worked with this closely. What was that unique experience like for you?

LENNY RUSH: It was great! And that was something that I was really looking forward to and was really happy that they’d done. It’d be horrible if they brought the kid in and then the show got a little bit more family-friendly. No one wants that. So I felt so lucky. I love Slow Horses anyway. I watched it [before I joined], and I was really lucky with my character. He was a lot of fun to play. The writers could have had a kid that didn’t speak much. He could just be there, but they made quite a bit out of the character, and I’m very pleased. We had a lot of fun. 

Reece quickly hits it off with Lamb. They feel a bit like kindred spirits. What was it like going toe-to-toe with the legendary Sir Gary Oldman?

He’s such a nice guy and so great; as everyone knows, he’s incredible. I think I must be the first person to say that I had a fart-off with Gary Oldman. [Laughs] But I learned a lot from him. He didn’t even have to give me advice; just watching him. I think he’s a great role model. And he was so normal. I probably chewed his ear off about The Dark Knight and Léon, and projects I loved, but he’d always make time for me. I really appreciated it, especially because I was a new cast member six years in. All of them made time for me; I had a lot of fun, and I love all of them. Chris Chung is incredible. Saskia Reeves is great. I learned a lot from her as well; she’s really wise and really kind. Everyone was just absolutely incredible.

I have to ask about Reece and Roddy, the most hilarious duo. What was it like developing that endearing love-hate relationship with Chris?

It was so easy, not in the sense that we hated each other, but because he’s such a nice guy and so easy to get on with. I remember the first day we met; it was like I’d known him for ages, and I felt free to chat with him and come up with ideas with him. He was so great. He was a bit of a big brother on that shoot to me, really, because I think most of my scenes are with him. Even if we don’t interact, he’s there. So I spent a lot of time with him. And I just love Chris as a person. I think he’s so funny. I still keep in touch with him today. He’s really lovely. 

I was so glad this role really let you flex your comedic genius. With such incredible writing, line deliveries, and performances, did you ever break on set?

The thing that I was lucky with is that in the fart scene, Reece is laughing, so I could laugh. If it was dead silence, I would have just been gone. I wouldn’t have been able to do it. But the character who always makes me laugh is Roddy Ho. I just love the stupid remarks he comes up with. It’s so offensive, and the funny part about it is that it’s Chris Chung saying it, who is so kind. Seeing him transform into Roddy Ho, who’s awful, is great. He’s a real treat to watch.

One of my favorite scenes of the season is Episode 4’s field trip to Shake Shack. I watched your Film Firsts with BAFTA video and learned you have a thing for villains, so how fun was it for you to verbally spar with Hugo Weaving’s Frank Harkness in that scene?

He is a great villain. And the thing that I love about Hugo Weaving as Frank Harkness is that he isn’t menacing-looking, and when he says stuff, it’s the way he says it. He says things so slowly and drawn out, and it instantly creates suspense. I chatted with him a lot, as well. To be honest, a lot of the behind-the-scenes was just me fanboying. [Laughs] But the thing about that Shake Shack scene that I loved is I go in, I insult Hugo, but then I don’t say anything until the end of the scene again. So I literally got my line out of the way, and then I could just sit there and watch Gary Oldman and Hugo Weaving do what they do best. I was just living in my favorite show. It was unreal. And I might be wrong, but I think it’s even Lamb and Harkness’ first interaction.