That last paragraph reads "Confusingly, in a typical English music session it is not at all uncommon to hear tunes from France, Sweden, the US or even Ireland. For English musicians, if the tune sounds good and fits into the general feel of the session then it’s worth playing and will be well received. But the bulk of the music played will be English."

In the few sessions I have been to in Ireland I have noticed something of the same trait, i.e. if the music feels right then they'll play it wherever it comes from. It's only outside Ireland that the session players feel they need to stay exclusively Irish. There are a few English sessions outside England in places like Stockholm and Toronto. I wouldn't be too surprised if they stuck exclusively to English tunes in the same way. I think it may be to do with playing the music of your country in your country and hence feeling relaxed about it.

Chris