For Downing, walking the school's halls was a homecoming as he returned to the classrooms that once nursed his musical theatre dreams.

Since then, Downing has toured the globe with the hit Broadway musical, marking his fifth season with the latest Australian production, which opens in Sydney later this month.

During some rare down time between shows, Downing and Durack took the chance to share their theatre experiences with some eager-to-learn musical theatre students.

"It's amazing to come back and do this because the school gave me so much," Downing said.

"I can remember sitting in the front row watching Wicked in Sydney six years ago while I was at school, so I've been in the students' shoes, I know exactly what it's like," he said.

"I've been so lucky in my work, so it's great to be able to share that with other people."

Durack, one of the nation's most well-known theatre performers, also relishes the chance to talk all things Wicked, particularly as the show has been her semi-regular home for many years.

The Helpmann Award winner played Glinda in the original Australian production and decided to return to the role when the musical re-opened in Melbourne last year.

"It's really like coming home; it's such a great role, so I couldn't wait to get back," she said.

"Glinda is such a fulfilling role - she's got this comedic side, great songs and there's some real depth to the character in the second act; I think it's one of the most fulfilling roles out there."

Wicked is the untold story of the witches of Oz, long before Dorothy dropped in.

The musical tells the tale of green-skinned Elphaba and beautiful Glinda and how they became the Wicked Witch of the West and Glinda the Good.

Durack admits the "Wicked effect" has worked its magic on audiences.

"It's just a beautiful show, it's one that only comes along once in a lifetime," she said.

"I think it's so special because it does have such a great story and beautiful music and the most elaborate, expensive sets. It's a show that just gets under people's skin; people really love it."

Wicked opens at the Capitol Theatre on September 25.

Tickets are available online at wickedthemusical.com.au or by phoning 1300 111 011.