DIANA Vickers has gone from The X Factor to the sex factor, first playing a "delightful Dominatrix" in the political farce The Duck House, and now the sexually innocent, all-American Janet Weiss in The Rocky Horror Show.

"It's very different," says Diana, a 2008 semi-finalist in the ITV talent show, who is appearing in York for the first time this week at the Grand Opera House. "Rocky Horror is a show like no other. I'd seen the film, which is a bit bonkers and off the wall, and I knew The Time Warp, but I still didn't quite know what I was letting myself in for."

Not to put too fine a point on it, Janet is called "Slut" repeatedly by audience members in this most participatory of musicals. "In rehearsals, the director yelled the 'shout-outs' at me, but that doesn't do the whole thing justice until you're out there on stage," says 24-year-old Diana, who made her debut over Christrmas in Brighton, where the audience "got really stuck in".

York Press:

Diana Vickers as Janet Weiss and Liam Tamne as Frank N. Furter in The Rocky Horror Show

"I was pretty petrified in rehearsals, though the director said, 'Don't worry, they're not going to eat you alive'. In the show you find you just have to stand there and take it, though the audience really like it when we corpse on stage and have a giggle. They love to see you 'break'."

Now Diana has settled into the role, there are still surprises in store. "The thing about this show is that just when you think you know it, the audience keeps it interesting for you, shouting out things you haven't heard before...or wearing things you haven't seen before, especially at the weekend shows," she says.

While Diana enjoyed the chance to be a pop star, signing to RCA Records on the back of The X Factor and topping the charts with Once in 2009, "my main goal was to be an actress," she says. "I used to go to the shows in London, thinking 'that's what I want to do'. Any variety I can have in my career is great; I couldn't just do musicals or be a pop star or make records, so I'm glad that I can do all these different things."

After her second album, 2013's Music To Make Boys Cry, Diana landed the shy, intimidated title role in the West End production of Jim Cartwright's The Rise And Fall Of Little Voice, for which she won the Whatsonstage.com Theatregoers’ Choice Award for London Newcomer of the Year.

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Diana Vickers

The role demanded the Blackburn-born singer could sing in the manner of Shirley Bassey, Edith Piaf, Judy Garland and Marilyn Monroe. "I hadn't explored my voice that way before, but then I found out how diverse it was, how powerful it was," she says. "To learn all these voices, I had to work very hard, like working with Tracie Bennett, a wonderful Judy Garland impersonator.

"I became obsessed with them, buying a record player and listening to all those Judy Garland and Edith Piaf records, but the thing is, it's hard to sound exactly like them, but you have to get the essence of their voice to bring them to life."

What followed was the aforementioned The Duck House, Dan Patterson and Colin Swash's West End farce prompted by the MPs' expenses scandal. "I played a student who was doing sexual favours for MPs for money. That was a  bit different from Janet, who's not a sexual fetishist at all, of course, but is rather innocent and prim and has to learn all about sex from Frank N. Furter [the 'sweet transvestite from transexual Transylvania']."

The Rocky Horror Show plays Grand Opera House, York, tonight until Thursday, 8pm; Friday and Saturday, 5.30pm, 8.30pm. Box office: 0844 871 3024 or at atgtickets.com/york