Absolutely Fabulous - Season 6 Episode 2 Darling!
Overview: When Saffron berates Edina for being lazy and incompetent, Edina and Patsy decide to impress her by booking her favourite French film star, Jeanne Durand, to perform at the Royal Albert Hall. However, they are dismayed when Jeanne refuses to sing aloud and instead merely mouths the lyrics. As a solution, Jeanne lip-syncs to Bubble's vocals on the night of the concert.