To put it more formally, apart from Australia and New Zealand, all human settlements have been in contact, however intermittently, with each other since their inception; music and entertainment are the most transportable of accomplishments, and in many cases musicians were and are itinerant. The concept of a "cultural group" having a exclusive musical style is at the least questionable. I believe that some research has ben done which indicates that all known "folk" ie pre renaiscence music is derived from a common base using the pentatonic scale. There is a reference to some of this work in the appendices to "Here I stand" Robeson P. (1958)

On the positive side I would suggest that the music of Robeson (which included many traditional songs from the British Isles) would be a good basis for research on your topic.

Please keep us informed of your progress.

Best of luck

Pete M