Usually the Dingo Dollar Challenges are a more light-hearted alternative to the ITV reality show's trademark Bushtucker Trials.
However, yesterday's task proved to be no less terrifying for Iain, who teamed up with Stanley Johnson to go 'channel hopping'.
Stanley had to sit in an armchair and watch a TV for numbers, which could be used to complete sums that would release the Dingo Dollars.
Iain's job was to tune the TV to the channels that would reveal the numbers, by moving its aerial to different positions.
The catch was that the aerial was on a high bridge, swaying a hundred feet above a jungle ravine.
Iain has made no secret of his fear of heights, and although he'd previously conquered the 'Space Your Fears' Trial, he was no less scared when facing the bridge.
"I’m not totally convinced I can do this," he said. "Let’s see how we go."
The radio host took two steps out, but was instantly unnerved. After a few more steps, he decided he couldn't continue and called an end to the challenge.
"Guys, I’m really sorry, I can’t do it, it’s off. Sorry Stanley," he said. "It didn't feel as sturdy as the rocket, there was nothing to hold on to."
Stanley did his best to reassure his teammate. "No-one knows how real people’s fear is," the politician commented.
"Who are we to tell a chap his fear is not real enough to take part in this escapade?"
The other celebs, awaiting a call from Kiosk Keith, were surprised by Iain and Stanley's early return to camp.
"It didn’t quite go to plan, but it wasn’t a disaster," Stanley claimed. "He gave it a go and then tried again also."
In the Bush Telegraph, Kezia Dugdale praised Stanley for being an "absolute gentleman" about the result.
"Stanley’s wise enough to know there’s a bunch of very macho boys in camp, who like nothing better than lording it over people, saying how much better they'd have done," she observed.
While the campmates insisted Iain shouldn't worry about what happened, some of the boys did question his efforts.
"He still should have done it, I don’t know why he didn’t do it."
Meanwhile, speaking to Toff and Vanessa White at the stream, Jamie Lomas said: "Bless Iain, I don’t think he’s cut out for this."
I'm A Celebrity… Get Me Out Of Here! airs nightly on ITV.