They'll play both if they sign up.
It's the only one they can play now- surely they wouldnt do European festivals without a stop in the UK?
Reading + Leeds will love GNR, unlike some of the twats at Download.
Arcade Fire, Blink 182, My Chemical Romance, Paramore (although they surely cant be a headliner but are 99% main stage)
keep your eye on efestivals.com on the Reading/Leeds rumours, because theyre ususally quite accurate, especially about a week before tickets.
Theyre still getting new reports so they have no 'almost certain' headliners apart from Blink 182 who are 99..9%.
Come on Leeds, sign up GNR!!!!
It would be EPIC.