Hugh Grant's homemade iPhone audition clip left the 'Unfrosted' writers "stunned".

The 'Notting Hill' star features in Jerry Seinfeld's comedy 'Unfrosted' as Thurl Ravenscroft – the actor who played Tony the Tiger for several decades – and his home-filmed try-out couldn't have gone down any better.

Recalling his audition, Seinfeld's co-writer Spike Feresten told IndieWire: “He had a glass of wine in his hand, and he was on the couch.

“We were just stunned on how homemade his audition was — and how good it was. Here’s Hugh Grant at 8 o’clock at night before he goes to bed, crushing the lines. Crushing. That’s when we said, ‘Jerry, close this for us. Get this guy.’”

It was no doubt a relief that Grant was perfect for the role because they were "terrified" of not being able to cast anyone.

Seinfeld - who also plays Bob Cabana, an employee of Kellogg's - said: “There was a long time where we didn’t have anybody to make this movie. We had the budget, we had the script, but we didn’t have any people to play the parts.

“That was one of the most terrifying moments. We would go into this little room that we had with each part on a 3×5 card on the wall. And we had [Jim] Gaffigan as Kellogg — and that was it. And there were like 30 parts.”

However, the 'Wonka' actor signing up led to other stars being interested.

He added how “a lot of other people started falling in after that.”

The Netflix film is loosely based on the true story of the creation of Pop-Tarts toaster pastries.

The cast also includes Melissa McCarthy, Jim Gaffigan, Amy Schumer, James Marsden, Jack McBrayer, Thomas Lennon, Bobby Moynihan, Maria Bakalova, Max Greenfield, Bill Burr, Dan Levy, and Christian Slater.