Here's a fascinating course by Simon Thoumire, for learners wishing to improve their playing of the English Concertina.
English Concertina Course by Simon Thoumire
This is a 4 week intermediate course. It is aimed at players who have been playing for more than one year or feel confident in their handling of their concertina and don't need to look at their fingers when playing.
Course objectives:
You will feel confident using your bellows You will be able to play different techniques including vibrato and advanced fingering You will be able to accompany yourself. Introduction to chord theory and modes.