Hollywood star George Clooney greeted fans as he attended the UK première of his directorial debut, Confessions of a Dangerous Mind, on Monday.
The former ER star shook hands and signed autographs for those who gathered for the event in London's Piccadilly.
Asked how he rated his film, he remained coy, explaining: "I can't have an objective viewpoint. I don't know if I'm a good boss."
The movie tells the story of legendary 1970s American TV producer and Gong Show host Chuck Barris, who is said to have led a double life as a CIA assassin
Actor Sam Rockwell, who plays Barris, arrived fresh from picking up a Silver Bear for the role at the Berlin film festival on Saturday night.
He said: "George is a fantastic boss. He's a really clever person."
The supporting cast includes Julia Roberts and Drew Barrymore, while Matt Damon and Brad Pitt have cameos as contestants on a Blind Date-style game show.
Clooney, who makes a brief appearance as a CIA agent, said: "When word got round we were making a film I got a call from almost every single A-list actor in town - not because they wanted to work with me as a director, but because these are such great parts.
"The idea of including Matt and Brad came to us on the set of Ocean's Eleven and to this day I can't believe they did it. It shows up what nice people they are."
The 41-year-old said he had not yet decided whether he would be making more films: "I'll direct again if something interesting comes
along," he said.
Other famous faces at the première were singer Tom Jones, actress Amanda Holden and critic Mariella Frostrup, who said: "I'm here for moral support but I don't think George really needs it."
In his autobiography Barris claimed he was a CIA agent, but many have cast doubt on the story.
Clooney said he decided to take him at his word.
I haven't seen that many in the UK, but I've watched Countdown
The star said: "I've asked Chuck about the specifics of the story and he would look me in the eyes and not say anything. I believe it is Chuck's story.
"I believe it was important for him to tell it and fun for us because the story is so wild."
Barris is regarded as one of the most influential figures in TV entertainment, creating seminal game shows The Dating Game and The Gong Show.
"I grew up in a world of bad television and I was around game show sets during that exact same period of time," said Clooney, whose father was a former host of 1970s quiz The Money Maze.
Asked which game show he watched in London, the star said: "I haven't seen that many in the UK, but I've watched Countdown."