Just a small point. Dev didn't lead Ireland out of the commonwealth -John A Costello did in 1949 . DeValera thought that if Ireland left the commonwealth unilaterally ,it would damage relations with northern unionists and stall Irish reunification. That is what did happen . After Costello made his announcement ,the British government passed a bill making unification subject to unionist consent.
I believe The Foggy Dew lyrics was written by a catholic priest . It certainly gets very mystical at some point , going on about seven tongues of flame shining over the lines of steel . There's an interesting thread about the English foggy foggy dew song elsewhere on mudcat . The tunes are different aren't they?