Brian:"What Alistair described in his workshop was not reversing the bellows as per the anglo. His point was that, since on the anglo one button controls two opposed reeds and their associated valves, when you change bellows direction one valve shuts and the corresponding one on the opposite side opens simultaneously, so one reed begins to sound at precisely the same moment its opposite is cut abruptly to nothing. That gives you very precise punctuation. The business of dynamics does not necessarily depend on bellows reversals"

Hmm, technically there is some point in that, but in practise ( You know as an anglo player..) it is only occasionally that you get two consecutive notes of the same button so that initiation/onset of the two notes is strictly "bellows-articulated" - at the moment of reversal as you say. In most activities there is some varying combination of finger-articulation and bellows-articulation. Anglo playing spontaneously stimulates more use of bellows articulation particularly for staccato while English players spontaneously use more finger articultion and many of them have difficulties creating a crisp staccato. AA certainly is one who has learnt to master this all the same. With Anglo on the other hand good legato playing can be a major challenge of course.

Concerning AA:s style he likely had some practise prior to the first recordings... but nevertheless intense English-playing puts a great deal of ( usually unhealthy)unphysiological stress on thumb joints, particularly the second one which may cause wear and inflammatory reactions.This may be counteracted by a proper wrist support combined with a hand/wrist strap so that the load on the thumb is reduced.

With the Anglo on the other hand *adding* a thumb strap may relieve the thumb from crampful muscular strain.
Most concertina players play seated despite the instrument may seem so handy for doing it standing.There are reasons for that....