When Richard O'Brien first brought the Rocky Horror Show to the stage in 1973, he thought it would play for three weeks, at most.
"I thought after three weeks everyone who would want to see this kind of entertainment would have seen it or missed it and we would go on to other things," O'Brien said.
"But, somehow or another, it touched a nerve, and here we are 50 years later."
Speaking ahead of the opening night in Adelaide of the 50th anniversary production, the 81-year-old said he felt like the "luckiest person on the planet".
"It's astonishing that I'm still here after 50 years … because I have taken a few chances, you know, smoked a few too many jazz cigarettes," he said.
"I was a hippie in the 60s. Well, I'm still a hippie, in many ways."
"I would say I'm the luckiest person on the planet. My children love me. My wife is my dearest friend and here I am still alive. Can't do better than that, can we?"
The Rocky Horror Show is the only contemporary rock musical to be continuously on stage somewhere in the world for half a century.
It was first performed in 1973 for an audience of 63 people in the Royal Court's Theatre Upstairs in London.
Its success saw it swiftly transferred to the Chelsea Classic Cinema, before running for six years at the Kings Road Theatre and then at the Comedy Theatre in the West End from 1979 to 1980.
The film adaption made more than $135 million at the box office following its release in 1975.
It has since become a cult classic, and its popularity continues to grow with its exploration of passion, sexual awakening and empowerment, combined with science fiction and hits such as The Time Warp attracting new fans with every passing decade.
"I don't think we thought we were pushing boundaries. We've got to remember that our director was a gay man, our art director was a gay man, I'm transgendered and we were playing and entertaining ourselves," O'Brien said.
Humble when asked about what he believed was key to the show's success, O'Brien said the Rocky Horror Show was a re-telling of fairy tales.
"It doesn't beat anyone over the head with a message … Brad and Janet are Hansel and Gretel. The wicked witch in the gingerbread cottage is Frank N Furter," he said.
"I think what Rocky does is allow us to remember the fairy tale but without knowing we are remembering it, so we are very comfortable with watching the story because we sort of know where it's going and we have certain expectations and they are fulfilled.
"Everybody comes on stage at the right time. All of the songs happen at the right time. The unveiling of the story as it goes along is reassuring to the audience."
O'Brien will take to the stage for three performances only in Adelaide as a special guest star alongside radio and television personality Myf Warhurst, who stars as The Narrator.
Making her musical theatre debut, Warhurst said she never expected to be cast as The Narrator.
"It usually goes to a sort of distinguished older gent, so I'm not sure what sort of drugs they took when they asked me to do the job, because I'm the opposite of that," she told ABC Radio Adelaide's Drive presenter Jules Schiller.
"Isn't it amazing? I never thought I would (be chosen), because I don't have any background in musical theatre.
"We did Spicks and Specks live shows, and they were big shows around the country, but I've never done anything like this."
Warhurst said she was "never more terrified" than when the show opened in Sydney, but described the overall experience as wonderful.
"I've just taken to it like a duck to water. I love it," she said.
"Not only was I working with Jason Donovan in Sydney — I could never have told my 15 year-old self that would be the case — but David Bedella is like an [Sir Laurence] Olivier award-winning actor.
"I'm like who am I? How did I get this lucky?"
Bedella — who plays Frank N Furter in the Adelaide shows — said O'Brien was incredibly humble about the success of his show.
"The beautiful piece that he's created has spanned the years … it's given people permission to be themselves. It celebrates rock n' roll and B movies and the 50s," he said.
"It's, in many ways, a family show and a morals show about love and the importance of steadfastness and trueness to each other."
Bedella said there was "no surpassing" Tim Curry's portrayal of Frank N Furter in the film.
"He's iconic. He's the creator. I wouldn't try to surpass him. I love him and I honour him. I hope I honour him in as many ways as I can," he said.
"We took great pains to change where I was coming from with the creation of my Frank. We made him American, which is very different to what Tim does."
