The basics of the Anglo system is in the two ten-button G and C-rows, as shown on 20-button concertinas. The 30-button concertinas already has the additional accidentals-row. There are some concertinas that have buttons with as many as 38 and even up to 45. However, you can play every single traditional music with just the 30-button instrument.
If your concertina is not a C/G, you can pretend that it is although it isn’t convenient. Whatever the tuning it has the notes and the scale has the same sequence. The result will simply be moved to a different key.
There are three main styles of Anglo playing: single note, harmony and octave. This book concentrates on single note style which can be approached in two ways. Play 'up and down' the home rows and be restricted to the instrument's two natural keys, great for morris particularly in G/D tuning, but in order to play this style to its full capacity, the more versatile technique of playing 'across' the rows is required.