Lily Collins has revealed the baby who played her daughter in Love, Rosie didn't like her co-star Sam Claflin.
Lily and Sam play best friends in the rom com based on the bestselling chick lit novel Where Rainbows End by Cecelia Ahern. Rosie's (Collins) whole life seems ahead of her until she accidentally gets pregnant from a one-night stand on the eve of her school leaver's ball and becomes a single working mother, while best friend Alex (Claflin) goes off to university and a new life in America.
Lily said of filming with the baby: "That baby did not like Sam! She kept crying and crying and crying whenever he's walk into a room. So finally we let the baby fall asleep and then shot the scene."
Sam added: "Oh God, the baby! It was meant to be me holding her so I looked like a natural dad, and every time I walked in she'd just scream. but apparently it wasn't just me, it was any man."
Lily admitted playing a mum had made her feel a bit broody.
She said: "It was lovely, little Rosa, who played Katie at five and Lily Laight who played her at 10, they were just so adorable. And their parents were on set so I got to see what worked with their relationship with their parents. Lily and I still keep in touch.
"It was really sweet - it just made me more excited to have kids."
The film follows Rosie and Alex over 12 years, from 18 to 30, and the pair admitted the vintage costumes they wore to play teenagers - though rather cringe-worthy - helped them get into character.
Lily said: "I felt like my body language and everything changed when I was at the beginning with the long sweaters and the jeans. I would hold my sweaters with my hands though them [the cuffs], like I did as a teenager."
Sam added: "I think the outfit I'm wearing on the poster is pretty hideous, but unfortunately that was the fashion of the early 2000s. And I think that was really fun and interesting when they started going 'This was fashionable back then, and I was like why?!'
"And I enjoyed the wig, weirdly. That nostalgic moment of doing this [flicking his fringe out of his eyes] as a 16-year-old boy. It all came flooding back."
Love, Rosie is out in cinemas on Wednesday October 22, 2014.