I agree with Mrs Duck - festival campsites have very poor facilities compared to even the most basic commercial sites and usually cost more. They are often very crowded as well - Camping and Caravanning Club sites require 6m between units for fire safety reasons and we have hardly ever had this luxury at a festival.
Perhaps we should start a thread comparing the campsites at our favourite festivals. Saddleworth probably gets my vote (although not last year when it was so wet and everyone wanted to be on the running track!)Saltburn festival is great but the camping is terrible - last time we went we parked up on the seafront!