I play Anglo, not English, and I don't use it for Irish music, so I don't know what I'm talking about, but in the finest traditions of internet forums I'm not going to let that stop me!

I wonder whether the reason behind Noel Hill's suggestion to English concertinists in his workshops to execute ornamentation on the same side as the note being ornamented is precisely because the left-right co-ordination is different on the two systems. Irish concertina style is based on the Anglo, where ornamentation is perhaps more likely to be played on the same side - playing on the opposite side may be slicker, may be more natural to English concertinists, may even sound better, but may not recreate the authentic style. Perhaps his suggestion is aimed at getting players of the English to achieve an "Anglo" style. Whether you consider this a good thing or not is up to you.