Samuel Welsh feels something of a heavy responsibility. In his first professional role since graduating from the Western Australian Academy of Performing Arts, the 23-year-old actor is playing the lead role in The 78-Storey Treehouse. It's based on the sixth volume in the popular "Treehouse" series of children's books by Andy Griffiths and Terry Denton.

Being a fan of Griffiths' earlier books like The Day My Bum Went Psycho from his own childhood _ "They're just wild" - Welsh is acutely aware of what a well-established phenomenon the author is, and he's playing "Andy" on stage in this new production.

"You've got to do justice to what they expect Andy to be," the actor, originally from Port Macquarie, says. But as well as the audience, he wanted its creator to be happy.

He talked to Griffiths during rehearsal and found he wasn't especially precious about how he was portrayed or how Richard Tulloch, who had adapted previous books in the series, brought them to the stage - obviously there's more freedom in the imagination than in the constraints of time and space and budget on stage.

"He said to me one day over dinner, you get so much freedom to do whatever you want."

In The 78-Storey Treehouse, Andy and his mate Terry (Teale Howie) are visited by a film director, Mr Big Shot (Tim Carroll) , who wants to big their adventures of Andy, Terry and their friend Jill (Freya Pragt) to the big screen. It's exciting news, but there's just one problem: Andy gets replaced by an ape.

"Mel Gibbon takes my role and Terry becomes the star of the movie, because Mr Big Shot feels Terry is funnier than Andy," Welsh says.

"Then it's about me trying to get into the movie with many tests of the friendship and more about the relationships with Jill, Terry and the director."

Andy discovers mysterious spy cows on the set and works out Mr Big Shot may not be all that he seems. But can he get his friends to believe him?

So far, Welsh says the response from audiences has been gratifyingly enthusiastic and the tour goes for nine months, a rare period of job security to have in a notoriously erratic industry.

He graduated from WAAPA's musical theatre course in 20016 having been accepted into it straight out of high school. He says he came to theatre relatively late.

"I was a sporty kid who did a lot of music when I was young. When I was about 15 my love of performing and making music overcame my interest in sport."

He became involved in extracurricular drama and dance and got involved in local theatre. His first stage role was as Sir Prancealot in a production of the pantomime King Arthur followed by Rolf in the Rodgers and Hammerstein musical The Sound of Music.

"I auditioned for WAAPA and was blessed enough to be accepted."

While there, he played Twig in Jay-James Moody's production of Bring It On: The Musical, as well as Ginger in the Australian premiere of Andrew Lloyd Webber's The Beautiful Game, directed by Meryl Tankard. After graduating at the end of 2016, he teamed up with Gold Coast-based company CherryCar Productions, playing the role of Len in the new Australian work The One-Armed Bandit. Since then, he also played the role of Will in Perform Musicals' book week tour of Super Duper. Then came the role of Andy.

This will be his first time performing in Canberra.

Also coming to the Canberra Theatre for the school holidays will be a return season of The Gruffalo, based on the book about a clever little mouse who deals with a forest full of predators by telling them stories of an imaginary monster friend - only to come face to face with that very creature.