Here's the Mudcat thread I had in mind, but it refers to a similar discussion in Chiff & Fipple, where it was pointed out that there are several songs along the same lines but with different tunes. One is Níl sé 'n' lá, the other is Níl 'na lá, and I've no idea what the third one is.A bit of unintentional forum-shopping going on there.