She's already playing Reading & Leeds and not headlining. We've had people headline Reading & Leeds in the past and still only sub, or headline Other stage
I think if Biffy Clyro are being swapped with any of the subs it'd be Paramore
Personally im going by the basis off what it's normally like. Extra stages, set ups and new arenas is just hearsay.
I can't see it being announced now, for me it would of all been announced when the initial headliners were announced.
For starters they would not be allowed an outdoor Stage of EDM post 11pm.
Just seems a bit fanciful.