Jo
Have you tried his FB page yet?
He, or a fan, might answer.
https://www.facebook.com/DaoiriFarrell/
or his website
http://daoiri.com/contact/
There are a couple of email addresses.

Or you might have to go to another gig and buy him a pint.

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I don't always find the song but when making a note of song lyrics I like I try to pick a phrase which sounds quite particular.
And when I write it down I put "quote marks" round the phrase. Otherwise it's all a messy jumble in my head
and on the paper.