There's an unspoken agreement in Hollywood that every artist – whether director or actor – must pay the requisite dues before getting his or her pick of bigger and better projects. Before Avatar, James Cameron gave us Piranha 2. Before next year's King Kong; Skull Island, Brie Larson gave us renowned indies Short Term 12 and Room. Before conquering Hollywood the Hemsworth Brothers, Heath Ledgers and Margot Robbies of the world trod the boards of Home and Away or Neighbours.

Usually an actor who stands on the stage of the Dolby Theatre, statuette in hand while thanking their agent, has already done a CGI-heavy blockbuster or studio comedy before landing the prestigious dramatic role that transforms a career.

So in going from lauded roles like Stephen Hawking in The Theory of Everything or Lili Elbe in The Danish Girl to playing opposite CGI monsters in a movie from the Harry Potter universe, isn't Eddie Redmayne doing things the wrong way round?

"Do I have a plan?" he laughs when Men's Style asks about his seemingly backwards career trajectory. "I love the idea that actors have any choice whatsoever. We're literally lucky to get employment. There were six or seven other actors who were offered the part for The Theory of Everything and I was lucky enough that they turned it down. I fought for it and got it and it just happens that it worked. Suddenly you're on a list for a moment, but that'll all shift and change in a year's time."

Of course, there are few more visible or beloved movie franchises at the commercial end of the spectrum for an Oscar winner to dive into in this day and age than the Potterverse. In Fantastic Beasts and Where to Find Them, the London native plays Newt Scamander, an anthropologist who's travelled the world collecting and cataloguing creatures from the wizarding world normally invisible to mere muggles.

It depicts the adventures of Newt and his new friends (among them Katherine Waterston of Inherent Vice and Steve Jobs) on the trail of escaped monsters in 1920's New York, the result of which is the textbook a young, bespectacled wizard-in-training and his friends will study at Hogwarts 70 years later.

But while Redmayne might not quite have his pick of scripts like we imagine, surely he only had to pick up the phone to director David Yates (of the last couple of Potter films) and author/scriptwriter J K Rowling and the role was his?

"You have to fight for all the [projects] you want that are outside people's expectation of who you are," he says. "Otherwise you end up being cast in the same thing again and again and again. You're always trying to prove the people who have preconceptions of who you are wrong."

He met with Yates in London a year before filming started and as well as feeling like the read-throughs with every other actor were proxy auditions for him too, Yates told him there was a list of actors he was testing to play the role.

The other difference about Fantastic Beasts is that in The Theory of Everything and The Danish Girl, all eyes were on Redmayne (and costar Alicia Vikander in the latter). Each role was about a very pure and all-encompassing sense of performance. This time he'll share the screen not just with the rest of the story's main foursome (costars Waterston, Dan Fogler and Alison Sudol) but a host of special effects and CGI.

It seems like it must be the actor's equivalent of a holiday, but Redmayne has the same air of commitment to Fantastic Beasts that led him to the Oscar stage to begin with, even though he enjoyed a different kind of acting. "One day I'm on a gigantic green bucking bronco been thrown around a room, shouting down at Dan and Alison and Katherine to put an insect in a teapot or something," he laughs, "then the next day there'll be an intimate, gently romantic scene with Katherine. There was such variety in it and I found it such fun."

He also says that even though he doesn't feel the spotlight pointed so intently on just his character, there's still a sense of direction to his choice of role. "With Danish Girl and Theory of Everything it was a responsibility to Lili's memory or Stephen's story. Here it's about the fans, it's about having had all these Harry Potter books and films and not screwing it up."

Along with a rapidly expanding CV that's broadening beyond 'awards magnet', the 34-year-old is also among the ranks of actors who seem to be cultivating a separate persona through brand partnerships. Are all those natty suits for fashion labels like Burberry and Prada the real Redmayne?

"In our lives [as actors] we don't have uniforms, costumes becomes a massive element of my process as far as finding who a character is. But when it comes to premieres and stuff like that, they're slightly silly things so why not use it as an excuse to get dressed up by all these amazing designers and their ideas?" he shrugs. "I do find it riveting though. I just did a campaign for Prada and hearing artists talk about the influences of their collections, it's the same thing actors do."

There's also the possibility – some would say danger – that wearing garb from designers who want to use you as a public figure to help sell clothes further obfuscates who you are to the world at large. Beyond just arguments about movie stars and famous people who sell out by appearing in fashion ads, the world might think of Eddie Redmayne as a guy who only ever leaves the house snappily dressed when he really lays around in stained trakky daks. Is the work with Prada et al just another kind of performance?

"That's a good question and I know actors who think we shouldn't do any of that because it removes from that anonymity or the idea of people being able to project onto what a character is, and I totally understand that. I was just lucky enough that when I was a kid doing plays for 300 quid a week and Christopher Bailey [Burberry] wanted to work with me. Doing those with him and now Prada, I find the process of working with artistic people interesting and enjoyable, I don't think of it as brand building."

But to the most important question. Marlon Brando's 1955 Oscar for On the Waterfront (a birthday gift given to Leonardo DiCaprio by his Wolf of Wall Street producers Red Granite Pictures) is missing, part of the embezzlement scandal surrounding the Malaysia-based company. Jennifer Lawrence's Oscar for The Silver Linings Playbook is back in her parents' bathroom in her native Kentucky. The final resting places of Oscars can be as interesting as the stories about those that won them. Where's Redmayne's Theory of Everything golden baldie?

"The Oscar sits on a little side table in my flat in London," he says, no such tall tale to offer. "It's very shiny and definitely doesn't feel real." Now entering the wizarding world of Harry Potter, it's a feeling he better get used to...