What you got back home, little sister, to play your fuzzy warbles on? I bet you got little save pitiful, portable picnic players. Come with uncle and hear all proper! Hear angel trumpets and devil trombones. You are invited.
Portishead will be playing a festival in England the week after Roo. A couple of acts playing that fest and playing Roo as well. Alt-J is one of them. It is not impossible for them to be a Roo. Unlikely yes, but not impossible.