'Waterloo Road's Zoe Lucker was "shocked" when her character hit her child.
The 38-year-old actress, who plays Carol Barry in the hit BBC One series, struggled filming the scene where the "feisty" mum-of-three lashes out at her on-screen son Barry (Carl Au), as she couldn't imagine ever smacking her own four-year-old daughter Lily.
She said: "When I read that I was going to hit my son I was pretty shocked, as it is not something I could ever do as a mum.
"Carol is physical with her kids, she is threatening, feisty and angry. She is a very hard woman.
"I couldn't actually hit (Carl) in real life, but when he saw the power behind my punch, I think he was really grateful I hadn't hit him across the face for real!
"It is very difficult to get to that stage in your head where it is OK to physically hurt someone.
"I have to take myself off into a corner and psyche myself up, before giving it as much as I can."
Although Zoe is nothing like her character she does feel "sympathy" for Carol - who is left to take care of Barry and her two daughters Kacey (Brogan Ellis) and Dynasty (Abbey Mavers) after her husband is sent to prison - as she knew people similar to her while growing up.
She added to The Sun newspaper: "Although I didn't base Carol on anyone, it is inspired by a couple of mums that I knew when I was younger.
"I do have an element of sympathy for Carol because even though she does behave quite appallingly a lot of the time, she has been left to look after three wayward kids when her husband is banged up for armed robbery."