Katy Perry at secret screening in London

Katy was more than happy to pose for pictures with her excited fans and sign autographs before sitting with them to watch the sneak preview of her 3D movie. She later tweeted a picture of her with the audience with the caption 'Had tons o' fun in London today at a surprise screening...Wish I could sit w/all of u when u see ?#KP3D ?(The movie).

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