Is he too good to be true?
Poor Sean. Saddled with an undeniable squeaky-cleanness, he'll never make it with the rude girls and boys. But he's got other things to think about. The former star of Dangerfield, and before that Aidan in EastEnders, and before that one of the lads in Grange Hill - and numerous film roles since the age of five (including grandson to Laurence Olivier) - is keen to test himself professionally. He is 20, after all.
Audiences too will be able to test his latest acting role in a cracking good film for the BBC Schools Scene drama strand called A Man of Letters, by Tim Firth. It is, he says, a more demanding role than he has ever played before.
"I was putting myself to the test to see if I could act this great piece of writing. It was more mentally and emotionally intense than anything I'd ever done. Before, I had always done guy-next-door roles," he says.
The film has Maguire playing Alan, a bungling slug of a trainee to Keith Barron's Frank, who has spent his lifelong career as a signwriter dreaming up Cold War thrillers that will put his name in lights.
Frank is the dominant character to Alan's young nerd in a china shop - until they realise that the sign they are putting up says For Sale. Frank's company is about to relocate - without him.
From then on, Alan comes into his own, using his warmth, youthful energy and creativity to pull Frank out of the emotional morass into which he has suddenly plummeted. He puts Frank's name in lights, literally.
It is a sensitive, gentle, well-crafted piece that shows off Maguire's inner light or whatever it is that makes him glow to such an advantage.
"I thought Alan's character was sweet, but more than that. Boys of 18 to 25 get a bad rap sometimes. But a lot of guys out there are like Alan - sensitive, caring, intelligent young lads who you never hear about," he says.
He would appear to fit into that category himself. Despite a successful career in acting and latterly as a pop star, with five hit singles to his credit since 1994, he recently went through a crisis of confidence, losing sight of his direction.
"Over the last six months, I was unhappy with my music, my work, myself. I was going to pack it in." Then he met a producer who inspired him to write new songs, "pouring my heart into more heart-led, thought provoking music". The upshot is "Today's the Day", which will be released in March. Will it make the charts? "It will either make me or be my last. Whatever, I'll be happy, " he says.
It is hard to picture many young pop stars being as philosophical about a make-or-break record. But then not every pop star freely admits to being an active Catholic without worrying about what it will do to his image. Maguire is incredibly candid about such unfashionable issues as what his faith means to him.
"As I got older, I realised that religion gave me structure, stability, piece of mind," he says. "I lead a better life for it. Even when I don't go to mass, I appreciate it for giving me the time to think about how I have been during the past week - have I been an ass?" Somehow, I can't imagine Liam and Noel Gallagher of Oasis sitting in the confession box spilling the beans. But I am curious about the professional dilemmas that could face an observant Catholic actor.
With all the incest, abortions, adultery and patricide that the regulars at the Vic and the inmates of Brookside Close have salivated over in the last few years, what would he do if he was ever asked to act a role that he considered immoral?
"If it were ever to come up that I was asked to blaspheme for an acting part, I don't think I'd take it. A part's a part - but religion's eternal."
Maguire's a good boy alright, but he's not gooey. He agreed to work with Christian Aid when they offered him a trip to India to make a schools video highlighting child homelessness. "My motives weren't entirely unselfish, " he can't help admitting.
Even so, he certainly got into the spirit of it all. "It knocked me sideways. I saw one light bulb for a whole village, people who had no water. I couldn't help feeling that Catholic guilt."
The fact that his video will be going into 16,000 schools should alleviate some of it.
Scene: A Man of Letters is broadcast on BBC2 on Friday, February 7, at 1.00pm