The Kid Who Would Be King is an old-fashioned film, and I don’t think Joe Cornish would mind it being called that. After some years spent contributing to studio scripts, the English writer-director follows up 2011’s Attack The Block with another tale of hearty contemporary misfits banding together to take on a deadly genre threat. The film is fuelled by issues of story-telling inheritance, drawing on Arthurian, fairy tale structures for a funny, down to Earth, quite moving tale of a young boy trying to figure out who he is. Alex (Louis Ashbourne Serkis) is a twelve year-old struggling with a…