Stroma's initiation began a little later, and when he walked up the Harry Potter and the Half-Blood Prince red carpet, he celebrated not only his screen debut but also a 2:1 BSc in neuroscience from University College London.

"Education has always been very important to me," says Stroma, who attended the Hogwarts-style Radley College, a boys' boarding school in Oxfordshire. "I enjoyed every minute there. It was a very good school with great facilities and great teaching. It was lovely and old-fashioned and they really taught their children how to be gentlemen. I was having so much fun that I rarely got homesick."

"When the BBC first announced the new cast members, I hadn't even started filming and yet there were all these websites, all having something to say about me. It was very bizarre. It was mostly complimentary, but because I do a bit of modelling as well, they'd got hold of my portfolio so all those pictures got around too. Now there are message boards about me: all these people claiming to be good sources saying things that are completely inaccurate, like my parents are divorced and stuff, none of which is true.

"It's not like there's any drunken photographs out there of me, it was just more the fact that they were my photos of friends and family; suddenly, everyone could look at them."

"There is that Hollywood scene of young stars who seem to get a lot of bad press, but Emma, Dan [Radcliffe] and Rupert [Grint] are such brilliant role models. There's simply nothing bad to report about them because they're all really lovely and they are down to earth.

"Maybe it's because they work so hard and it's been one film after the other –and they've been doing it since they were 12 or so – and they work such long days. They must have time to let loose or whatever, but they're working constantly so they grew up quick, I think. They learned how to behave themselves and I imagine they must have had good role models around them to look up to."

If Stroma's post-Potter career doesn't pan out, then he already has a back-up plan: "If my dramatic career doesn't work out, I will go on to research and find cures for Alzheimer's or Parkinson's and other motor neurone diseases. It's a very exciting field of research. But I'd like to continue in drama so it wouldn't be very smart of me if I blew this amazing opportunity with an inappropriate lifestyle."