Apropos John's comment,the Salvation Army used to run a school at Likoni in Mombasa where they had a concertina band. There is a photo in one of Neil Wayne's Free Reed magazines. As far as I know, the concertina has not taken off in Kenya. Perhaps it is because it is too expensive and not suited for the many styles of Kenyan music. The guitar on the other hand has been adopted widely.
By the way, although not really relevant to this discussion,Idi Amin used to play melodeon.
Simon