Here's a really silly question, from someone who's listened to a lot of Peter Bellamy but never picked up an Anglo. Where do you get the chords? What do you do on a G/D box if you're chording along to a song that's pitched in A or F - or if you need to find a G7 or a Dsus4?

Make that two silly questions. I accompany myself at a fairly basic level on English concertina, and when I listen to a chordal accompaniment on EC I can usually take a stab at what's going on. But when I listen to Bellamy playing On Board a 98 or Death Is Not The End I've got no idea what he's doing; technically it sounds pretty rough, but it's rough in some way I can't begin to imitate (on EC). There seems to be a different chord for every note of the melody line - how was he doing it? Or was he just playing the melody line plus odd thirds and fifths?