Here is his performance in the final, in which he sings about appearing in the contest:
He wins a £250,000 cash prize, and a spot on the next Royal Variety Performance.
Courtenay was initially too overwhelmed to talk to hosts Ant & Dec. The below video shows him being announced as the winner. He revealed he had woken up that morning with an idea for a song for the Royal Variety Performance, and said that winning had "changed his life".
Ant & Dec had picked the comedian as their "golden buzzer act". Here is his previous semi-final performance:
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