Celeste Barber on loving and losing her closest friend.

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Celeste Barber struggles to remember the first time she met Mark Priestley. It may have been when she first starred on All Saints in 2005, or perhaps before. The actor had such a strong presence in her life, it just feels like he’s always been there.

Even now, 10 years after his death, that hasn’t changed.

Speaking to Mamamia‘s No Filter podcast, the actor/writer/comedian and Instagram sensation said she speaks often to her children about Priestly.

“I have this real fear that if you don’t talk about them they never existed. I know we’re lucky enough to have footage and stuff of Mark, but it’s very important to me,” the 35-year-old said. “That might be selfish because there are people that go, ‘I don’t want to talk about it’, and that’s fine. But I’m not one of those people.

“My [two sons] never met him, my step daughters, I don’t think, ever met him. And I find that the hardest to deal with, because I’m like, he was everything and he can’t not have ever been here. It freaks me out, that idea.”

Celeste talks to Mia Freedman about Mark. (Post continues below.)

Priestly was just 32 when he took his own life in September 2008.

Barber knew he was unwell; she saw the impact of his mental illness up close. But she also saw the creative side of him, the enthusiastic, the comedic, the one bursting with ideas. The side of him that would knock on the door of her Sydney apartment at three in the morning to write or film an original script.

Barber and Priestley’s friendship was built on comedy; it’s how they connected, personally and professionally.

“He was just an idiot, and I was too. We’re both just really full-on about the same kind of things – about comedy and being loud and doing our own stuff. And we just ran at each other with that,” Barber said.

“He would always give me shit on [the All Saints] set, because he knew it would rile me up. He’d go, ‘Well, at the end of the day, women aren’t funny.’ And he knew [I’d take the bait.] We’d just run around set screaming at each other.

“He’d always try and get me in trouble. Just that really immature shit that I think, as adults, we all crave.”

But it was in a more serious moment that Priestley most shaped Barber’s comedy. While working on one of their scripts between All Saints scenes, she balked at a funny line.

“I was like, ‘Nah, I won’t say that part; don’t worry about it.’ He just looked at me and went, ‘Can you stop that? Just stop that. It’s boring. You not getting that what you do is great is boring. So stop,'” she said.

That advice still guides Barber as she populates her hilarious Instagram account with parodies of celebrity photographs. She’s earned 3.3 million followers and international coverage as a result.

“That was a massive moment for me to go, yeah, it is boring to ask for other people to validate if I’m funny, or if what I’m doing is OK. He was like, ‘You know it is, so don’t f**king worry about anyone else. Keep going. Go, go.’ And now I do,” she said. “It was nice, and it’s all thanks to stupid Mark.”

You can listen to Mia Freedman’s entire chat with Celeste on No Filter. Post continues below.