Dozens of volunteers to perform to Singin’ in the Rain in Cardiff Umbrella Flash Mob   Led by Cardiff/Barry based Gemma Hillberg of Turnd Up Fitness and dancers from across the city, Cardiff’s Singin’ in the Rain Umbrella Flash Mob will be taking place at Chapter as part of the BFI’s UK-wide season BFI Musicals! The Greatest Show on Screen.   On Saturday 19 October at 2pm, dozens of Cardiff volunteers will gather at Chapter to perform a dance…