Audiences at the Edinburgh Fringe, the largest arts festival in the world, may think they’ve seen everything. But this year, women and girls from the red light districts of Mumbai will be treading the boards for the first time in the festival’s 70-year history. Their play, Lal Batti Express (Red Light Express), includes dancing, singing and storytelling. The performance forms part of the Fringe’s Just Festival, which focuses on social justice. A film by James McLaughlin