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Singer Mel C joined the cast of the School of Rock West End musical for a surprise encore performance of The Spice Girl's Wannabe at the New London Theatre.
Video footage posted on the School of Rock UK Twitter pageshows Mel singing one verse solo before the rest of the cast join in.
For the encore, lead cast member David Fynn, who plays Dewey Finn, the character portrayed by Jack Black in the 2003 movie told the audience that they were in for a surprise.
"Ladies and gentlemen, for this evening only, we've got a very special encore for you," he said. "We've learnt it for one evening. This was number one a long time, 21 years ago, one of the rock great classics, this is, from the Spice Girls, Wannabe. You can get your cameras out for this one."
She tells the audience, "Thank you, aren't they amazing? Thank you very much. Girl power."
Her shock performance comes almost a month after her former Spice Girl Mel B broke out of character as Roxie Hart during a performance of Chicago The Musical to perform her Wannabe rap.