In a wide-ranging interview with Tim Minchin, he discusses the ins-and-outs of writing Matilda, Groundhog Day, Larrkins, acting and his move to LA: so much that I’m breaking it into two parts.

The second part, coming soon, will focus on Groundhog Day, Larrikins and his move to Los Angeles. In this first part, he talks about his encounter with a (fictional) little girl called Matilda.

When the Royal Shakespeare Company was looking for someone to write the songs for their musical of Matilda, director Matthew Warchus went to see one of Tim Minchin’s solo shows in London.

As Minchin tells it, by the show’s end Warchus had decided that he wasn’t right for the job. Then as an encore, Minchin sang White Wine in the Sun, his beautiful, heartfelt song to his baby daughter Violet about Christmas, family and love, and Warchus changed his mind.

“He was thinking, ‘no’ and then he went, ‘oh, there’s another dimension’. I’m so glad. Can you imagine? It’s made such a profound impact on my life, this musical, and my whole career,” says Minchin.

Based on Roald Dahl’s popular children’s book, Matilda the Musical has proved a phenomenal success. It won a record seven Olivier Awards in London and four Tony Awards on Broadway, where the New York Times described it as “the most satisfying and subversive musical ever to come out of Britain.”

The Australian production begins previewing in Sydney on July 28. Minchin, who grew up in Perth, will be at the official opening on August 20 and says it feels “genuinely special” to be bringing the show home to Australia.

The feeling is reciprocated. Matilda is probably the most hotly anticipated musical of the year in Sydney where the love affair with Minchin continues to grow. Tickets were snapped up in next to no time when he played two sold-out shows on the steps of the Sydney Opera House in February. He held the ecstatic audience in the palm of his hand, with more than a few tears during White Wine in the Sun. His own mascara seemed to run a bit too.

And when he came to Sydney last October for the launch of Matilda, Destination NSW took the opportunity to honour the self-proclaimed “rock ‘n’ roll nerd” with a plaque in Sydney’s Theatre Walk at Walsh Bay, joining the likes of Cate Blanchett, Geoffrey Rush, Jacki Weaver and John Bell.

Minchin was a star before Matilda. A comedy songwriter with trademark ratty hair, kohl-rimmed eyes and bare feet, his genius for combining pithy, witty, pointed lyrics with catchy tunes had already won him such a cult following that he could fill arenas for his solo shows and front symphony orchestras in concert halls.

But Matilda has made him a superstar, in demand around the world. He is now writing songs for a musical based on the 1993 film Groundhog Day, also directed by Warchus, which will premiere at London’s Old Vic next year prior to a Broadway opening in 2017.

He is also the songwriter and director for an animated DreamWorks movie called Larrikins, set in Australia, scheduled for release in 2018. There’s a film of Matilda the Musical in the pipeline too.

“Without Matilda, I could have gone more down the path that people who get known for comedy go on but this has taken me back to what I was doing as a kid. I wrote loads of music for the theatre in my late teens and early 20s,” says Minchin.

“Then I started getting a couple of roles in plays and I moved to Melbourne and then I got frustrated because no one would take any notice of me and so I started doing comedy. But even at the beginning of my comedy career I was writing musical scores.”

In 2004, he wrote the songs for This Blasted Earth, a Christmas musical written with Travis Cotton and Toby Schmitz, which played at Sydney’s 40-seat pub theatre at the Old Fitzroy in Woolloomooloo. In 2005, he and Kate Mulvany wrote Somewhere, a musical about Penrith for the opening of the Q Theatre. That same year, he won the Best Newcomer Award at the Edinburgh Fringe Festival.

“It does strike me as really amazing that (working on Matilda is so similar to) what I was doing 10 years ago,” he says munching on jelly snakes to keep himself awake as he battles raging jetlag.

“I listen back to those songs I wrote for the Old Fitz show and the songs from Somewhere and there are definitely songs in the Penrith musical that are as good as anything in Matilda. There was no change in tools; there was just a change in status, in who was asking me to write for them.”

Funnily enough, in a now famous anecdote, while he was writing music for theatre shows in Perth, Minchin – who is mad Dahl fan from way back – enquired about getting the stage rights for a musical of Matilda. When Dahl’s estate asked for a sample of his score, he panicked and dropped the idea.

“It’s a great story. It doesn’t sound very believable but it’s true,” he says.

Matilda tells the tale of a smart, book-loving little girl who uses intelligence, imagination, courage and magic to defy her mean parents and vicious, tyrannical headmistress Miss Trunchbull.

As Minchin puts it: “The show’s about a tiny person starting a revolution to overthrow the oppressors.”

Minchin’s songs are absolutely brilliant: funny, bolshie, poignant and refreshingly different to so many of the pop scores of contemporary musical theatre. In retrospect, it’s hard to think of anyone else more suited to the task. His intelligence, irreverence, wit and heart seem such a perfect match for Dahl.

“Matilda feels a particular way. It doesn’t just feel like me, it feels like me interpreting Dahl,” he says. “There’s an angularity to the opening and this semi-tonal thing going on. The dominant movement through the whole thing is a semi-tonal shift with all these crunchy harmonics. In musical theatre, it’s usually big shifts and fourths, not semi-tones. But I do think Matilda has an aesthetic that seems to work.”

You might think the first thing Minchin would have done after being commissioned by the RSC was to pick up Dahl’s novel again, but no. Instead, he looked to the show’s book by writer Dennis Kelly.

“I never went back and re-read the book because I decided Dennis’s adaptation was my source text,” says Minchin. “I didn’t re-read all my Dahl. I just had an utterly convinced sense that I knew what Dahl-ness was and I knew his themes. Obviously there’s that cheeky little tip-of-the hat to Roald Dahl’s Revolting Rhymes: ‘We are revolting children, Living in revolting times, We sing revolting songs, Using revolting rhymes…’ (Hooley-dooley, Tim Minchin is singing for me). I was taking from all Dahl’s work without even knowing I was doing it really.”

When Minchin came on board, Kelly had already been working on Matilda for a year.

“He had a script adaptation and he said, ‘I’ve (marked) some places where I think there might be songs, I’ve even written a few lyrics,’” recalls Minchin. “And I said, ‘you can’t give me any lyrics or song titles. I just want “song here, question mark” and we’ll discuss what you think they might be about, because you might have a great idea but how will I know if I have a better one if that gets in my head?’

“So he gave me a script with no songs and Matthew (Warchus) and me and Chris Nightingale, the orchestrator, who was in from the very beginning, and Dennis just talked and talked and talked. Your most pretentious, in-depth tutorial in an English Literature of a university got nowhere near the level of textural analysis that we were doing!

“I went away and broke it down and put songs in different colours representing different styles, so if it was a chorus number it was this colour and if it was a solo number it was another colour and all that sort of thing, which kind of mapped it. I didn’t start writing songs until we had a really strong map.”

Hard though it is to believe now, Minchin reveals that at one point they considered making Matilda a non-singing character.

“Early on, Matilda had no songs. I couldn’t work out how to make her sing, weirdly, because she’s so quiet. Then I wrote Quiet,” he says.

“That’s not quite true. She had a song in the second act where Quiet is now, which is just as she is about to do magic for the first time. It had this big rumbling build-up to ‘Magical! but we all went, ‘that’s not right’ so when we did the first workshop we just discarded it. She had no songs at that point and we were considering the possibility that she might not have songs; that the world revolves around her and she is a still force.

“There was another character called Hortensia who had two big songs, Revolting Children and another called Now That She’s Gone when Trunchbull leaves. It’s a really funny song but it didn’t belong in the musical and nor did Hortensia so she got dissolved and we gave her spirit to Matilda so she can sing, ‘sometimes you have to be a little bit naughty’ – the language of rebellion.”

One of the most well-known and popular songs in the show is the sweet When I Grow Up. The idea behind it came from one of Minchin’s own childhood memories.

“I remember promising myself I would never open the farm gate. We used to spend a lot of time when I was growing up on my grandfather’s farm and you would always climb over the gate or flip over the gate. I’d watch the oldies fiddle with the (padlock) and I would go: ‘I hope I never have to walk through gates. Gates are to be hurdled,’” he says.

“That idea of looking at things as a child and promising yourself that as an adult you’ll do all the things you think are awesome as a child (is the idea behind the song). It’s somehow sad because you are so wrong. Or maybe you were right. That’s the point. Dahl would say that we forget that kids have the wisdom. We’re sad as adults because we don’t climb trees and eat sweets and wake up with the sun. That’s where all the melancholy comes from in that.

“As you can tell when I talk about these things, I tend to go, ‘oh, here’s an idea and if I do that….’ That’s how I find my way into things. There’s a lot of emotion to be got out of thinking your way into it. But I think having young kids really allowed that.”

Asked if he does still leap the gate, he grimaces a bit. “No. I’m a bit sore these days. But when I run I have a compulsion to jump up on picnic tables. I’m like an old shitty Parkour runner.”

When I Grow Up is the first non-narrative song Minchin wrote for the show. “It’s a reflective piece, although in the musical Miss Honey sings the last verse about being brave enough to fight the creatures, which gives you a hint of what’s to come,” he says.

“When I Grow Up always sat outside the piece and one of the ways it doesn’t now is because I took the whole thing and wrote a new tune over the chord structure and that’s Naughty. It’s basically the same song. Naughty and When I Grow Up are almost identical harmonically and that’s why they go from one to the other in the mash-up (at the end).”

Thinking back on the robust working relationship between him and Kelly, as Matilda gradually took shape, Minchin laughs with genuine pleasure.

“He’d never written a musical before. We tugged and pulled and pushed for the whole writing period. We didn’t know each other very well early on and Matthew would sit there quietly letting us fight it out. Then he’d say one sentence and we’d go, ‘right’. He’s such a genius and so quiet. But we’d all make each other laugh all the time.

“Dennis Kelly is now one of my favourite humans on the planet,” adds Minchin. “We’re from very different backgrounds and we approach art in a different way. I don’t know but perhaps if you write something like this and it goes so well, you are bonded by a very positive experience. As the time went on, I just fell in love with him. He’s such a brilliant guy.”

Matilda plays at Sydney’s Lyric Theatre from July 28. Bookings: Ticketmaster 1300 795 267

 A version of this story ran in the Sunday Telegraph on June 28