In this nostalgic and joyful one-off special, we tell the stories behind the greatest ABBA covers of all time by some of the biggest artists in the world. This features Cher, Andy Bell of Erasure, Neil Arthur of Blancmange, Carla Bruni, Adrian Utley of Portishead, Dannii Minogue and William Orbit, who talks about a lost cover by Madonnna.