Slow Horses actor Christopher Chung looks completely different in Australian Idol audition from when he was 16

He's best known for starring as British MI5 agent and tech specialist in Slow Horses, but years before his on-screen fame, Christopher Chung appeared on an entirely different show.

The 38-year-old actor has appeared in all six seasons of the Apple TV special, which centres around a dysfunctional team of disgraced MI5 agents and their boss.

Chung previously appeared in episodes of Neighbours and Doctors, had a prolonged stint on Waterloo Road, and starred as a ‘geek’ in Sky Movies HD adverts before scoring the major gig.

He recently put down his flourishing career in acting to his sister in an interview with Luxury London.

He told of how she regularly starred in amateur musical theatre shows in Melbourne, and that he became fascinated by how much she was enjoying performing.

By age 12, he took his own first steps into the world of performance when he was cast as the lead in the stage show of Aladdin.

“Those are my earliest memories,” he said. “It was at that point that I remember thinking, ‘Ok, I guess this is what I’m doing for the rest of my life."

But before making it on the big screen and with a love for singing, he featured on music competition show Australian Idol.

The singing show aired its first season in July 2003 and ended its initial run in November 2009. It originated from the reality program Pop Idol, which was created by British entertainment executive Simon Fuller.

In an old clip, which has resurfaced on X, Chung can be seen belting out Stevie Wonder's 1970 soul hit 'Signed Sealed Delivered (I'm Yours).'

"Before he was Roddy Ho on Slow Horses. Christopher Chung on Australian Idol at age 16," the caption wrote.

"Hilarious, didn’t realise this," one user responded, as a second person commented: "That is not ladies man Roddy Ho... I’m crying."

Chung once acknowledged his Australian Idol appearance during an interview on Triple J.

Laughing at the clip, he said "Controversial. That is so savage. That was the original dream.

"I thought I was going to be a pop star. I actually did Popstars Live before I did Australian Idol. His voice hadn't broken. He was 16."