"a session is incidental even if it is obtrusive. " I like that way of putting it. Very neat.

I can envisage a court case hinging in producing evidence thta a regular had told the barman how he rather wished those diddley buggers in the corner would shut up. This would serve to prove that the music was not entertainment but was incidental and obtrusive.

Basically, we'd better not start playing too well, or the publican will get in trouble. Nothing much to worry about then...