However, after the premiere his efforts to escape photographers backfired. His driver parked at the front of the Soho bar - while he and Snowdon were stuck in the alley.
The star was trapped there for 10 minutes as efforts to find the missing vehicle went on, prompting his extraordinary outburst.
Snowdon, 31, a model and TV presenter, had made a surprise visit to the West End premiere. Earlier Clooney had said he was "really happy" she came to support him, but said he was flying back to Los Angeles just hours after the screening.
Snowdon, who split from the former ER star this year, was asked if it was all back on. She laughed and said: "No, we're just friends."
The film, a thriller set against the backdrop of the communist witch-hunt in Fifties America, has earned rave reviews. It closed the 49th London Film Festival.