This is based on The Select, which is a play by Elevator Repair Service, which is based on The Sun Also Rises by Ernest Hemingway, which is just based on his life it turns out.
Keira Knightley admitted that she agreed to appear in Never Let Me Go because co-star and friend Carey Mulligan had asked her to. When asked what she did and did not have in common with her character, Knightley said she was unable to relate to Ruth’s situation of being involved in a love triangle.
(Source: filmtrivia)