A number of other cast members walked the red carpet, including Tom Hiddleston, Cobie Smulders and Mark Ruffalo.
Elsa Pataky, Sam Claflin, Laura Haddock and Jasmine Guinness also attended.
The Avengers is released in UK cinemas on April 26 under the title Marvel Avengers Assemble and on May 4 in the US.
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