"Mo Ghile Mear" (My Gallant Darling) was sung by Una Palliser in the Specsavers TV ad with the sheep and sheep dog. According to Wikipedia, it was written by Seán Clárach Mac Domhnaill in the 18th century.

Fisherman's Friends have made a couple of TV ads for Young's frozen food, with adaptations of "What shall we do with the drunken sailor" and "When the boat comes in".