Co-star Anne Hathaway admits the get togethers quickly became a weekly highlight and a chance for the cast to dust off their treacherous and desperate characters for an evening of fun and friendship.
She tells WENN, "You cannot underestimate the contribution from Russell Crowe. He was the first to say, 'Hey, come to my house Friday night. My voice teacher is gonna play piano, we'll have a couple of drinks and we'll sing.'
"Through those nights, Russell let us approach singing from a completely different perspective which was, 'This was our language through our shared experiences'.
"I could've just gone home after my part but I really wanted to know how did (song) On My Own go or the other songs turn out. It really cemented the bond between us. Now we kind of say we're Camp Les Mis. It cannot be understated that we're all massive Les Mis geeks!"
And Hugh Jackman admits there was a very special bond on the set, which made the filming experience unique: "One of the first days of filming I was singing in this beautiful old church in London and I remember I came up these winding stone steps and Annie (Hathaway) was at the top and she came over and had tears in her eyes and she was hugging me. I've never known that on a film before.
"We were all there for each other. It had the feeling of the closest stage show but it was a film. We will be bonded for life for what we went through."