Who is there first makes no difference to a noise nuisance, if its a nuisance its a nuisance. From person who in the past has enforced this legislation. I remember objecting when houses were proposed next to a dog kennels, in fact all around them. The council objected, the contractors appealed, the Government granted the appeal and the houses were built. We then got complaints re barking dogs. The Council then paid to move the kennels some where else. If this had not been possible the Kennels would have been served notice and closed. Lucky for the kennels owner, as a council we were reasonable.
What is reasonable is at the heart of Noise Legislation, most enforces of the Control of Pollution Act are reasonable people and attempt compromise. I personally have only served notice when the person creating the noise have, themselves, in my opinion been unreasonable and where I believed that magistrates, Judges etc would agree with me.
Please remember there are two sides to a complaint and don't let your own personal thoughts re folk music etc obstruct what the "Mythical Reasonable Man" would think as reasonable.
Sorry if I used the word reasonable more than a reasonable number of times.