Actually they're not. They are the headlining support act, The Cure are Headlining the main stage on the day Paramore are playing.
Ah I thought there were 6 headliners - Cure, Paramore, Kasabian, Black Keys, Florence and Foo - and they swapped round so one is last on for Reading and one is last on for Leeds. Must have got mixed up. Ah well they are one step away then.