It's almost a decade since Katie Leung broke a million hearts when she gave Harry Potter his first proper kiss. After beating more than 3,000 other hopefuls to land the part of Cho Chang in 2005's The Goblet of Fire, Katie, now 28, kissed the boy wizard two years later in The Order of the Phoenix.
In One Child you play Mei, a Chinese-born woman who was brought up in the UK after being abandoned by her mother because of China's controversial one-child policy. A journalist then contacts Mei from China - what happens next?
"The journalist pleads with Mei to return to China to save her brother from being executed for a murder he didn't commit. I think to begin with, she goes out to China out of curiosity. It's a way for her to find closure, having been brought up as an adoptee wondering about who her mother really was. For me it's definitely more about Mei's own personal needs than a desire to save her innocent brother from execution."
As part of your research, you spoke to a woman who had lived your character's life, having been adopted by a British family after being given up by Chinese parents. How was that experience?
"It was really nice, actually, because after coming on set and speaking to the drama's writer, Guy Hibbert, this person was encouraged to go out and seek her own birth mother."
We understand you got a chance to meet up with your own mother when you shot scenes in Hong Kong, where she lives?
"Whenever I'm in Hong Kong she takes a few days off work so we can go shopping, although it was quite difficult this time because there wasn't much time between filming."
Looking back on Harry Potter, were you nervous kissing Daniel Radcliffe?
"It wasn't the kiss itself that made me nervous, but the fact it was so hyped up. It was like, 'Oh my god!' I mean it was a closed set, but people were still watching on the monitors outside and, looking back, it wasn't a comfortable experience. I can't watch the films now - I just cringe. Making them was an enjoyable and crazy time, though."
Have you had any weird Harry Potter experiences recently?
"A few months ago, a guy walked past me shouting, 'Harry Potter, Harry Potter, Harry Potter!' What are you meant to say to that?!"