Alexandra Billings has clapped back at famed stage producer Cameron Mackintosh over comments he made regarding the casting of transgender actors as cisgender characters on stage.Mackintosh, the producing dynamo behind such smash hits as Les Miserables, Mary Poppins and The Phantom of the Opera called potential casting of a transgender woman as Mary Poppins “gimmick casting,” and said doing so would be “trying to force something that isn’t natural” in an interview with British outlet The Telegraph.Billings, never one to hold back, took to Instagram to issue a harsh rebuttal.A post shared by Alexandra Billings (@therealalexandrabillings)“Sir Cameron,” Billings wrote, “I am playing Madame Morrible in Wicked on Broadway.