Tom Cruise said playing heroic loner Jack Reacher was "easy" because it reminded him of his own life.
The Top Gun star spent hours meeting fans at the premiere of his new film in London's Leicester Square.
Jack Reacher is based on One Shot - one of the series of best-selling novels by Lee Child about the eponymous former soldier turned drifter who travels the United States dealing out his own brand of justice.
Child - real name Jim Grant - said he knew Cruise was the right man for the role when he saw him carry on with work on set despite a serious hand injury.
The author, who was born in Coventry and grew up in Birmingham, said: "He's reckless like Reacher."
Cruise's co-star Rosamund Pike said she loved working with the man she described as "the greatest movie star of my lifetime".