Coronation Street actress Millie Gibson was left visibly shocked to discover a mysterious element about the This Morning set.
The actress, 18, who has played Kelly Neelan on the cobbles for the past four years, joined This Morning hosts Alison Hammond and Dermot O'Leary to discuss her departure from the ITV soap - but she was left highly distracted by the famous This Morning window which looks out onto London's River Thames.
Millie was shocked to discover that the iconic window is actually fake after growing up watching the show thinking it was real.
The soap star, who is leaving the cobbles after four years, recently filmed her final scenes on the soap as Kelly, was discussing the incredible technology which Corrie producers used for her dramatic last scenes - as ITV bosses roped in some of the best Hollywood equipment for the hotly-anticipated episode.
Millie then admitted that she was left flabbergasted to learn that the ITV window was also kept running by technology after believing it was real.
"I can't believe it! I thought that was real for my whole life. I thought it was a window," she gaped.
"I was wondering why it always looked so sunny in London," she added.
And it seems Millie wasn't the only one surprised to learn the famous window was fake as stunned This Morning viewers flocked to Twitter to share their disbelief.
"As IF I actually believed the This Morning window was real all this time!!! What in the world," quipped one fan.
"So you're telling me it's fake?! My mind is blown," another added.
"Me and Millie must be as thick as each other because I always believed that window was looking out onto the Thames too," someone else joked.
While a fourth insisted: "Come on guys!!! The same boat has hardly been going up and down the Thames for years on end."
It comes after the actress recently explained the reason she quit Coronation Street after four years.
Millie has set her sights on other acting roles after her involvement in some of the most dramatic storylines on the cobbles in recent years.
The talented soap star revealed that choosing to leave Corrie was one of the most difficult decisions of her life, but insisted that she had to "trust her instinct".
And before she leaves, it looks as though there's quite a shocking twist in store for the character's final scenes.
Lifting the lid on her departure from the show, Millie explained: "I have no responsibilities – I don’t have kids, I don’t have a mortgage to pay or anything like that, I’m still grateful to be living at home.
"So I thought I’m just going to see what else the world has. If it does, it does - that would be quite good, wouldn’t it?
"I just thought I might as well see what happens while I’m still young," Millie told The Mirror.
The actress went on: "Because I’m so young I thought I’ve got to leave. It was a decision where it would always be in the back of my mind if I didn’t make it, so I had to just go with it and see what happens."
Millie previously starred in the CBBC show Jamie Johnson.
The actress took to Instagram to pay tribute to her co-stars with a gushing caption.
Alongside photos of all of her Corrie pals together, Millie penned: "Now that the news is out about me exiting the cobbles, I just want to say I've had the most incredible 4 years.
"Growing up here, I've made long lasting friendships, learnt so much and I am forever grateful for my time and the storylines I have been given.
"I'm really looking forward to you guys seeing the future episodes coming up and I can't thank [Corrie] enough for letting me be a small piece in this beautiful family."
The actress - who a British Soap Award for her role earlier this year - further commented: "Kelly Neelan will be apart of my heart always. Thank you to you all for being so supportive."
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