'Call the Midwife' writer Heidi Thomas is ready to axe stars who intend to use the show as a stepping stone to make it in the US.
Th 56-year-old screenwriter has become cautious about signing up "young" stars who have Hollywood in their sights and admitted she has become "quite ruthless" about putting stateside hopefuls to "one side".
Speaking to the Daily Star newspaper's HOT TV column, she confessed: "Writers don't have control over whether people stay or not.
"And when young ladies come on the show and then three years later they decide it's time to go to Hollywood every time, it's like a stab through the heart.
"I now know the signs and when I see those signs I think: 'Oh Hollywood beckons' and I start to think how I will move them to one side.
"I become quite ruthless about it."
The BBC One series has helped launched the careers of Jessica Raine - who played nurse Jenny Lee from 2012 until 2014 - who featured in 'The Woman in Black' alongside Daniel Radcliffe in the same year she started on 'Call the Midwife'.
And Emerald Fennell, who portrayed nurse Patsy Mount until 2017, and had a role as Elsa in 2015's 'The Danish Girl' alongside the likes of Eddie Redmayne, Alicia Vikander, Ben Whishaw and Amber Heard.
Most recently Emerald took over from Phoebe Waller-Bridge as head writer on global phenomenon 'Killing Eve' for season two.
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