On Saturday night (12 April), viewers saw 79-year-old Paddy and dance partner Nico perform a spectacular salsa routine.
Simon wasn't impressed with the act at first, and soon pressed his red buzzer, but that all changed once Paddy unleashed her energetic dance moves.
Paddy's flexibility earned her a standing ovation from fellow judges Alesha Dixon, David Walliams and Amanda Holden, as she was tossed and twirled on stage by a youthful Nico.
Amanda also pressed the coveted golden buzzer, giving the pair a pass straight through to the live shows.
Despite the judges' joy, Paddy and Nico's routine came into dispute after the show, as it emerged that the pair had won Spanish TV talent show, Tu Si Que Vales (You Are Worth It), back in 2009.
Defending the salsa-dancing gran, Simon said on Twitter last night (13 April): "Don't knock Paddy for performing on a Spanish talent show. She is British and wants the chance to perform in front of our Royal family. Let her have that chance. You the viewers will decide."
The return of Britain's Got Talent was a ratings hit on Saturday night, as it achieved its highest ever launch episode with 11.1 million viewers.
Simon added this morning: "A huge thank you to everyone who watched Britain's Got Talent on Saturday. The ratings were really good."
What did you think of Paddy and Nico's performance? Will their previous win affect their chances? Tell us below, as the best comment from across the website each week wins £50!
Watch Paddy and Nico's performance below: