I came across this from an interview recorded by Alan Lomax some time in the 1950's with Irish street singer Margaret Barry, found on "Margaret Barry: I Sang Through the Fairs" on Rounder Records:

"It's actually what you call a 'sociable'. In houses they carry on like that. Because they love that sort of life—the dance you see. It's what they call a house-ceilidh. A house-ceilidh.
And of course, it's only natural enough, it's never without a drink.

[We'd] be playing all the time and singing, and [we'd] get a little rest around ten o'clock—just a little rest in between. And a little bit of supper. And if there was room in the place around—take away the furniture and tables and the whole lot—and just start off playing and dancing until one o'clock in the morning.

Oh, yes. Then while [we'd] be getting a little refreshment, well they'd all have a recitation. Some of them would be able to sing, and more of them couldn't sing; they'd have to say something, because that's the sort of a place it is around here. Everybody has to do a turn, while [the musicians were] getting this little bit of a feast, whatever time it would be. And then [we'd] start on playing again."

People sang to fill in the gap while the musicians were otherwise occupied.