The This Morning presenter was surprised earlier this year with an opportunity to appear on the long-running detective drama, after years of being a superfan.
However, speaking about her part with Phillip Schofield on Tuesday, Willoughby said that she wasn’t making space for an acting Bafta on her mantlepiece just yet.
She said: “Well, you know, I wasn't 'take one' put it that way. Or take two, or take ten.
“About take 25 I finally got the words out, but it's fine!"
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"I had a few scenes, but one line and I couldn't get it out! But I had a really good day,” Willoughby then added.
Schofield cheekily asked her: "Do you think you'll get invited back?", to which she responded she “didn’t think so”.
Details are still firmly under wraps about the TV presenters’ role, with the new series of Midsomer Murders currently being filmed across Berkshire and Buckinghamshire.
Willoughby was surprised with her role back in March, when stars Neil Dudgeon and Nick Hendrix appeared on This Morning to surprise her.
Towards the end of the interview, Dudgeon told her: “We’ve all had a big talk about who we want to appear on Midsomer, and we decided we want Holly Willoughby to appear in an episode of Midsomer Murders very soon.
“I’ve been speaking to people upstairs and they’ve been speaking to your people.
“Holly please, I am emboldened here to offer you a role in Midsomer Murders.”
The excited presenter immediately said yes, but warned: “I mean, you’re going to have to kill me off really quickly as I’m terrible at acting.”
“That’s never held us back in Midsomer!” the actor laughed back.
She then requested she be killed by chocolate, as she thought “that was the way to go”.
Midsomer Murders has become famed for its bizarre and inventive ways of killing victims, with a wheel of cheese, a slow-moving tank, and electrocution via exercise bike all being used in the past.
Midsomer Murders returns later this year on ITV.
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