She joins comedian Norman Pace and The Voice’s Liam Tamne in the touring show coming to Milton Keynes Theatre from Monday July 25 to Saturday July 30.
Diana said: “It’s a bit of a bonkers show, but our characters start off quite virginesque and naive and then they get lured into Frank N Furter’s world and they just become liberated.
“To me, it is inspired by all the B movies and the science fiction films but it is something much more different.
“It is a show that I really wanted to do. I’ve always given everything into the audition and I think it is a role that a lot of actresses would want this role and I am so glad it was given to me.
“If you want to see something that you will remember for the rest of your life, then this is the show to come to.
And there are several moments within the show which Diana loves.
She said: “I do have one solo which is a great moment because it is the moment that Janet becomes a woman and the lyrics are great.
“But my other favourite moment is when Frank N Furter is revealed. It’s a great moment in the show but it is a great moment to play. I love playing Janet reacting to that moment because she has never seen anything like Frank N Furter before.
“I am happy to do a mixture of the two but I would much prefer to do the acting. That is the thing that gets me out of bed in the morning and drives me.”
She first rose to prominence on the fifth series of The X Factor eventually won by Alexandra Burke and it was a turning point in her life.
Diana said: “I look back at The X Factor with a lot of great memories. I was 16 at the time and I was living the childhood dream of being a popstar.
“It was nine years ago and never had an issue. It was extremely exhausting at times but I was glad to have enjoyed it.
“It will be a big moment in my life.
One of her most recent theatre sucsesses was in Little Voice, a part she loved doing.
Diana added: “I also really liked doing Little Voice on stage. I started to be aware of these fabulous divas, people like Marilyn Monroe and Judy Garland. In a way, I became the character of LV, sat there at night listening to these great performers and trying to imitate them.”
She has also embraced musical theatre and is due to appear in the adaptation of the movie Big.
For tickets to The Rocky Horror Show, call the box office on 0844 871 7652 or visit www.atgtickets.co.uk/miltonkeynes.