The above link is to where LACORS, along with what it refers to as its partners, have produced joint guidance on the incidental exemption which LACORS refer to as the DCMS Guidance.
As this joint document gives examples of bands qualifying for the incidental exemption this 'DCMS guidance' seems to differ to LACORS own submission to DCMS where LACORS want to make "make it clear that music involving multiple instruments is very unlikely to fall within the incidental music exemption."
I wonder if their so-called partners have been consulted before LACORS submitted this further requirement of their own or indeed if they are aware of it now?