Dance Theatre of Harlem, 1976In 1968, at the height of the civil rights movement, Arthur Mitchell and Karel Shook founded the Dance Theatre of Harlem in New York. Six years later, they toured Britain for the second time, which is where Guardian photographer Denis Thorpe captured them rehearsing at Manchesters Opera House in the summer of 1976. Thorpe, who knew the dancers by reputation, recalls how he knew he wanted to freeze the moment when all the dancers were off the ground.