Robert Downey Jr
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Robert Downey Jr on what is special about Iron Man 3

19 April 2013 Last updated at 13:40 BST

Stars of the new film Iron Man 3 have been in London for its premiere.

The event should have taken place two days earlier, but clashed with the funeral of former British prime minister Margaret Thatcher, also known as the Iron Lady.

The film's leading actor Robert Downey Jr talked to the BBC's Lizo Mzimba about the challenges for his character in the sequel.