Re song accompaniments: how many concertina players have a choice?
Keith Kendrick is one of the few people in the world who can play both English and Anglo systems well, and he mostly uses the English for songs and the Anglo for tunes.

On the other hand, amongst concertina systems I play Anglo only, and use it mostly for song accompaniments these days, and Mary plays English, and uses it mostly for playing tunes now. But with respect to Doug's post - I'm not singing while I'm playing, except for the odd simple chorus.

The English concertina has the advantage of being reasonably easy to play in any key. As usual there are exceptions - Harry Scurfield told me he has one song he sings in B major (yes, five sharps), accompanied in that key on a C/G Anglo. It just happens to work well that way, he said.

Anahata