Told by way of a retrospective, this is a stylish and informative - if not always very entertaining - biopic on the legendary film star. He is discussing his autobiography and as he meanders down memory lane, we accompany him from his life in Edwardian London through his journey to the USA where he found fame with Keystone Studios and developed the legendary "Tramp" persona that resonated so well with an increasingly poverty-stricken populace. Robert Downey Jnr is effective in the title role, conveying much of the quirkiness - and selfishness - of this character. Geraldine Chaplin (his real…