> Prometheus complete coverage
The Anonymous actor told Digital Spy that he can't discuss the 3D science fiction movie in depth because Scott has been strict about not leaking out information.
He said: "It was so top secret. There were security guards on set, Ridley doesn't want people to find out about it. One thing you learn in life is you don't mess with Ridley! He's amazing, an incredible director and perhaps one of the great, living genuine film auteurs."
Spall added of the eagerly-awaited prequel: "Fans of the genre won't be disappointed, and people who have never seen the Alien film won't be disappointed. I think it's going to be brilliant.
"It felt like being part of movie history, dare I say!"
Prometheus stars Noomi Rapace, Michael Fassbender and Charlize Theron and will open in cinemas in June 2012.
> Anonymous Rafe Spall interview: 'I could see myself showing off in a frock'