Pixar scrapped three quarters of the Toy Story 4 script

“Usually, it takes – from start to finish – two years. But because they threw most of it in the bin and started over [my time on the project has] been extended a little bit. I've done a lot of work on it.”

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With a smile, Potts added: “They're funny those Pixar people. They just take their time. It's very painstaking work. If they don't like whole sections then they just chuck it and start over again. They have that great creative liberty to do that.”

Potts also revealed that at one point she believed her role had been cut from the film altogether or that the entire project had been cancelled. “I didn't hear from them in a year and a half,” she said.

It wouldn’t have been the first time she'd been cut from a Toy Story film. Although she voiced Bo Peep in the first two hit movies, Potts wasn’t asked to return for the franchise's third in 2010. “That hurt my feelings a little bit,” she said. “But John [Lasseter, Pixar's chief creative officer] explained to me the reason was because they were saving me for 4.”

And it looks as though Peep will have a large role in Toy Story 4. Although we previously knew the film would follow Woody and Buzz’s search for the porcelain shepherdess, Potts confirmed the missing toy would still enjoy plenty of screen-time. “I have a big part! I'm thrilled!” she said.

Despite the majority of the script being re-written, Potts hinted the plot Lasseter teased in 2014 – a "love story" between Bo and Woody – would still make it to screen.

Speaking about her time in the San Francisco recording studio, she said: “Most of it is with Tom [Hanks, who voices Woody]. I've never done any animation before where you got to work with the other actors. [Normally it's] just a single voice at a time. But because of the nature of what we're doing, we've been having Tom and me together. That's fun! That is really fun!”

Potts also recently reunited with Wallace Shawn ­– who voices terrified Tyrannosaurus Rex in the animated films – but not for Toy Story. Shawn enjoyed a guest spot on Big Bang Theory spin-off Young Sheldon, in which Potts plays the grandmother/'Meemaw' of the titular neurotic nerd.

But although Shawn plays her love interest in the show, it’s the nine-year-old Sheldon actor, Iain Armitage, that Potts can't help talking about: “He is very nice with beautiful manners. And beautiful professional manners. He’s particularly wired in his performance.

“When we started working together he'd just turned nine, so every once in a while we do have to say, 'You need to focus. Can you be with us?'. He's very hard on himself if he feels like he's wandered a little bit. And usually, he'll come back after the scene is done and say, 'I'm very sorry I wasn't focused! Very sorry!'”

While Potts describes her time with the show’s young cast as “magical”, there is one scene that’s a struggle to film. “We always say that the two scariest words on Young Sheldon are 'family dinner'. They are six of us and it's very tedious to shoot. And the kids are trapped in their chairs. It's always excruciating!" she laughs.

“It takes a very long time. For every line said, the camera has to move. If I'm talking to you then we have to get that shot and ones of other people reacting. Then we do the same when you say things to me. It's round and round and round. I don't even know how directors figure that out!”

Young Sheldon is on Thursdays at 8pm on E4