The King's Speech director was mulling over his cast choices when he caught Hathaway serenading Jackman while co-hosting the 2011 Academy Awards - and he immediately knew the stars would be perfect as his Fantine and Jean Valjean.
Hooper tells WENN, "I remember I was sitting at the Oscars two years ago and was in the middle of this difficult decision about whether to do Les Miserables. I was kind of close to saying the final 'Yes'. Anne Hathaway was hosting and at a certain point she came to the front of the stage and sings On My Own to Hugh Jackman.
"I'm sitting there going, 'There's something very strange happening here!' My shortlist for Fantine started with Anne Hathaway and my shortlist for Jean Valjean starts with Hugh Jackman. She's serenading Hugh and I thought, 'They're brilliantly using the Oscars for an auditioning tool.'
"It certainly worked because I ended up casting both of them. Both of them are so comfortable expressing themselves through song that you kind of rather they didn't break into dialogue.
"I was incredibly impressed that Anne was working with her legendary voice teacher, Joan Lader, six months before the shoot on how to produce the belt sound; that very powerful end of her voice while keeping her face relaxed so that she knew when the camera was close-up she could have that necessary stillness. She also admitted that she practised crying and singing."
And Hooper reveals Jackman has secretly been preparing for Les Mis for years: "I never saw (Jackman's stage show) Boy From Oz, but I did see his one-man show. He claims to me that the reason he did his one-man show was to get himself vocally fit for Les Miserables."