He might have only been playing a solo acoustic set on the second stage at Sauchiehall Street's ABC, but Willson's set – and that song in particular – captured the spirit of the day: rousing, a cherished new discovery to some, played to a packed and receptive crowd, all united against the foul, bone-saturating weather hindering progress between this year's five participating venues.
Beginning with an afternoon-long session at the Captain's Rest on Great Western Road, the festival bloomed into a frantic evening series of sets by new bands from across Scotland and the world. Timing crossover between some of the biggest names was unfortunate but necessary, although two factors really made this day's entertainment great: the unerring quality of the genre-spanning line-up selected, and the sheer novelty factor of most.
Even old-stagers like Liverpool's Clinic aren't regulars on the touring circuit, while, for example, Glasgow's Admiral Fallow are experiencing a fresh wave of national support that plays up their Mumford & Sons comparisons and Edinburgh indie-poppers Kid Canaveral might be underexposed before a Glasgow audience.
As far as headliners go, however, the day was all about two bands. Upstairs at the ABC, Los Angeles' painfully hip all-girl shoegazer outfit Warpaint played a set which was euphoric in the most leisurely way, a sonic arrangement that was as slow-moving and purposeful as the tide coming in. Later, at the Art School, Glasgow's criminally underrated Sons & Daughters debuted songs from their excellent upcoming fourth album Mirror Mirror. Hopefully it will be the album to give them the level of recognition they've long deserved.