The cover art was created by photographer Bob Seidemann, a personal friend and former flatmate of Clapton's who is primarily known for his photos of Janis Joplin and the Grateful Dead. In the mid-1990s, in an advertising circular intended to help sell lithographic reprints of the famous album cover, he explained his thinking behind the image.
I could not get my hands on the image until out of the mist a concept began to emerge. To symbolize the achievement of human creativity and its expression through technology a space ship was the material object. To carry this new spore into the universe, innocence would be the ideal bearer, a young girl, a girl as young as Shakespeare's Juliet. The space ship would be the fruit of the tree of knowledge and the girl, the fruit of the tree of life.
The space ship could be made by Mick Milligan, a jeweller at the Royal College or Art [sic]. The girl was another matter. If she were too old it would be cheesecake, too young and it would be nothing. The beginning of the transition from girl to woman, that is what I was after. That temporal point, that singular flare of radiant innocence. Where is that girl?
Seidemann wrote that he approached a girl reported to be 14 years old on the London Tube about modelling for the cover, and eventually met with her parents, but that she proved too old for the effect he wanted. Instead, the model he used was her younger sister Mariora Goschen, who was reported to be 11 years old. Mariora initially requested a horse as a fee but was instead paid £40.
Just a temporary dye. Gotta figure out how to do it so that it doesn't get all over my skin. 
