The "English" concertina system button spacing is different from other systems like common Anglo-German or Maccann and Crane duets.The English has a transversal c-c button interspace of 12,7mm while the Anglo and Duet got 16mm and standard full size computer keyboards(18-)19mm.The adult human hand corresponds to the later measures but not to the small size of the English system.The historic reason for the difference likely may be that the "English" keyboard was an off-spring from the keyboard of the Symphonium (the keyed mouthorgan/harmonica described in a Charles Wheatstone patent 1829)and the outspoken intention that the English concertina should be played by using 1st and 2nd fingers only.

Tradition has conserved the dysfunctional measures while modern playing habits and general comfort motivates a reformation, something which may be carried out without major obstacles when new instruments are ordered/produced today.