I have learned such a lot from the replies here. Thank you very much to guybarry and martinswede. Extensive replies take such a lot of effort and you have both done this very well.
Because I am only coming to music for in this way for the first time (in retirement now lol) I used the theory because it was what I could understand. Having information from practitioners puts a whole new perspective on it for me.
Thank you
John Lundrigan