And in Blackwood for Jan. 1831 ("Noctes Ambrosianæ, No. 53.") is "A Christmas Carol in honour of Maga, sung by the Contributors," which begins thus—
"When Kit North is dead,
What will Maga do, Sir?
She must go to bed,
And like him die too, Sir!
Fal de ral de ral,
Iram coram dago;
Fal de ral de ral,
Here's success to Maga!"
I suspect that the "chorus or refrain" of the first of these ditties suggested that of the second; and that this is the song which was running in your contributor's head.