Could this affect the picnic? www.wirelessfestival.co.uk
Oh crap! As Mitty said, I wonder how far out their festivities will stretch. It's a huge park and there may be other suitable places in the park if the festival pushes that far out.
I have sent an email to the wireless festival people and if I don't hear back I'll give them a call on friday and see if I can get some answers about this.