Hopefully not indeed! Perhaps it will just be a second slot for Enter Shikari as a stage opener - they are listed for midday on their own website. Edit: Earache say Saturday night - so unless it is stage opener on Town Centre then not that.
So Earache Records put out a clue about their secret guest (Saturday)... they have headlined the John Peel stage in last 10 years. A quick scan of wikipedia puts this as the following rock/heavy options. Ash, Enter Shikari (doubling up?), Crystal Castles, Biffy Clyro, Suede. Ash are playing Boardmasters on the Friday so perhaps most likely.