TBF, even the BST shows are multiple stages, even though they’ve got comparatively small bills compared to a full festival. Wouldn’t surprise me to see the four acts already announced on the main stage and a further support bill of around 8/10 artists scattered across the other two stages.
They need to make the other stages bigger than the ones at BST though. That tent was absolutely RAMMED for Owen Pallett, Phosporescent and Caitlin Rose on the years I went. Far too small.