Great pleasure to be keynoting at the excellent Generations and Genealogy in European Literature conference: here’s Tagore, Faculty of Letters @speccoll-kuleuven.bsky.social : observed huge student social event: why is ‘The Bonnie banks of Loch Lomond’ such a hit among Belgian students??
So you were there during the (former) student cantus, with the bells. For more info on cantusses, see Wikipedia. Which songs are sung depends on the what is in the 'codex' at a time of the event. Most of them are traditionals, I don't think the one you mention is more popular than other.
Thank you so much for explaining, I so enjoyed my visit to your university/city