Niall Ashdown appeared briefly in the British edition of Whose Line.
Predominantly used as a singer, Niall didn't make much of an impression on the show. He also seemed to be the go-to guy for accents, showcasing as many as possible in one of his credit readings. Perhaps his most famous moment was as Bartender to Greg Proops (who in the game of that name had lost his virginity). Greg sang about losing his virginity to a woman who turned out to be Clive Anderson, to which Niall sang back a verse that ended with, "When you look like you, you got to get it where you can!"
Niall's appearances (UK)
Series 7: Episodes 1 and 11
Series 8: Episodes 8, 9 and 13