Reading Jim Bainbridge's contribution above reminds me of a singaround that he was part of in the early 1970s. It was at one of those wonderful TMSA festivals at Kinross which has recently moved there from Blairgowrie.
Tina and I had been sensible enough to hire in advance one of the permanent caravans on the campsite for the weekend. After the late, late events in the pubs and hotels, things continued in the 4 or 5 big caravans that were at the top of the campsite. We had invited quite a few friends and, of course, Jim was among them but many more than that squeezed in. Even before it began, industrial amounts of alcohol had been consumed. Where I was sitting, I was unable to move my feet because the space was taken by Dave Goulder who was peacefully 'resting his eyes' still clutching a half empty bottle of a single malt to his chest.
Belle Stewart turned up and could barely squeeze inside the door. Before she gave us her song she said, "Of course. Alex and me have got a big posh room at the Kirklands Hotel, but we jist thocht we'd com' an' see hoo a' you puir travellers are managing camped oot in a' weathers!"
Aly Bain could not get in but he leaned his fiddle inside one of the open windows and gave us a tune.
John Watt had appointed himself as compere and even through very bleary eyes, he was doing a very good job, He was sitting next to Alex Mackie and had asked Alex to sing. Alex was singing Bonnie Gateshead Lass - starting at a normal pace, he gradually sung slower and slower before passing out before he reached the end of the song. John gave him a few pokes, but failed to revive him. "Ach weel, Ah want ye's a' tae be here at 10.30 in the mornin' tae hear Alex finish his sang. Noo, we'll hae a sang frae Cathal."
Eventually the singaround broke up not long before dawn. We managed to revive Dave and a few other sleepers and made a sustained effort to get Alex removed. This was particularly important because at that time, Alex was the World and European Heavy Snoring Champion.

We have been to hundreds of informal singarounds at folk festivals since those days, but somehow these more recent ones lack the human interest that the ones at those early TMSA festivals offered.