Rock icon Roger Waters was left humbled on Saturday (06Sep14) after fans at a Toronto International Film Festival screening serenaded him with a rendition of Happy Birthday.

The former Pink Floyd frontman was set to introduce the world premiere of his new documentary Roger Waters: The Wall at the Elgin Theater in Canada this weekend, when he was surprised with an impromptu sing-a-long as he entered the auditorium.

Waters, who turned 71 on Saturday, expressed his shock and gratitude by letting slip an expletive as he marvelled at the packed house.

He returned to the stage after the screening to partake in a question and answer session with fans about the film, which documents his latest tour, during which he performs the seminal Pink Floyd album.