I have no vested interest in Chippenham and wasn't at this year's festival.
what I found a little strange was that ...
a. neither the landlord/manager of the pub, nor anyone from the festival attended the licensing committee hearing.
b. the online programme for the festival does not mention a folk festival event in the evening in that particular pub.
c. nevertheless, everyone seemed to accept that the event that was noisy was part of the folk festival (whereas all the evidence is that it wasn't). No doubt the landlord used the marquee in the garden facility to put a non-folk band in there (or else it was an informal festival session).