Hugh Jackman and Kate Hudson on the musical alchemy of “Song Sung Blue”

Last week, at a New York bar called Old Mates, Australian icon Hugh Jackman sang a few songs by an American icon, Neil Diamond. He’s been doing a lot of this lately.

His new film, “Song Sung Blue,” is based on the real-life story of Mike and Claire Sardina, celebrity impersonators who teamed up to form a Neil Diamond tribute act by the name of Lightning & Thunder. Jackman was cast early on as Mike, and director Craig Brewer was still looking for someone to play Claire, when Jackman got an idea from watching TV: “Yeah. It’s this little-known show, ‘CBS Sunday Morning,'” he said. 

In…