West End star Lee Mead talks about his first ever TV drama role, in Saturday’s Casualty on BBC1…

Can you tell us about your character Harry?
“He’s a teaching assistant and he’s just started at a new school. It’s quite run down – he’s used to teaching in places that are better run – and on his first day Harry encounters this aggressive young student called Lee. This lad really puts Harry on edge, he’s never experienced anyone like him before.”

So what happens?
“Harry’s boss is a teacher called Emma (Pookie Quesnel), who takes him under her wing. When Lee is aggressive towards Harry, Emma reprimands the kid, who goes to grab her arm. She turns and slaps Lee on the face – it’s the first time she’s ever laid a hand on a student in 15 years of teaching. It’s pure impulse.”

Bad move! How does Lee react?
“He goes mad and smashes up the classroom. Then Lee gets his hands on a fire extinguisher and throws it through a glass door, before attempting to dive through the door and collapsing on glass and cutting himself. It turns out that Lee has learning difficulties. He’s very aggressive and has lots of issues, but as the show unfolds we discover that Lee’s actually a good kid.”

Does Emma get in trouble for slapping a pupil?
“Emma knows she’ll never work again unless Harry tells the doctors and police that she didn’t hit him. She asks him to hide the facts. He does initially, but he gets confused because he’s not someone who wants to hide the fact that this poor kid has been slapped…”

Is this your first TV acting role?
“Yes, and it’s been a great experience for me. One of my first scenes was with Derek Thompson, who plays Charlie, and it seemed really surreal because I’ve been a Casualty fan for years. I’ve starred in musicals for 10 years and it’s been wonderful to do shows in the West End, but I’ve wanted to act in film and TV for a long time.”

So you’re going to do more?
“I would love to! It’s funny because in 2006 I was going to stop musical shows completely to study acting. Then a TV show called Any Dream Will Do came up and I auditioned… and my whole life changed completely.”