@ Steve I sort of knew you wouldn't mind really! But thanks anyway. I read bits of Bishop in the Roud/Bishop book on English Folk Song. Sounds interesting. There is an excellent online course (MOOC) called 'The Fundamentals of Music Theory' which people might like to try. It's run by Edinburgh Uni (if they still do it). https://www.eca.ed.ac.uk/study/short-course/fundamentals-music-theory-mooc