And despite the rain in the British capital, the stars of the show were out in force, from Gemma Arterton to action man of the moment, Avatar's Sam Worthington.
Looking every inch a Grecian goddess in a gorgeous Gucci gown, Gemma, 24 - who plays Perseus' mysterious spirit guide, Io – had her hair swept up to appropriately reveal a new wing tattoo behind her left ear.
She did not, however, show any signs of the numerous grazes she received while making the movie – many of the stunts were performed by the actors themselves.
"There's make-up on my legs to get rid of the clash rash," she admitted. "They're recovered, it was a few months ago now."
For the sword-wielding lead Sam, who takes on the role of Perseus, preparing for the film was equally as arduous and required him to train for six hours a day for two months to get into shape.
But there was one aspect he was not completely adverse to when it came to playing the mortal son of Zeus – wearing a skirt.
"I didn't mind it," said the 33-year-old England-born Australian star said. "I tried to get mine shorter. But when you've got Christmas hams like mine and ricotta thighs, the boys kept saying: 'Bring it down, no one wants to see that!'"
Nearly thirty years on from the 1981 original, which starred Dame Maggie Smith and Laurence Olivier, the Clash of the Titans remake tells the story of Perseus and his perilous mission to Argos to battle god of the Underworld, Hades, played by Ralph Fiennes.
The film also stars Liam Neeson as Zeus and features a cameo from model Agyness Deyn, who appears as the goddess of love, Aphrodite. It will arrive on cinema screens across the globe from April 2.