Screenwriter Peter Morgan was keen to have his cameo in new movie 360 axed, because he hated his experience in front of the camera.
Jude Law and Rachel Weisz star in the romantic drama and Morgan was talked into filming a small part to keep costs down.
However, he hated his day "sitting around on set" and admits the experience put him off any more acting roles.
Morgan tells the Bbc, "That was horrible. I won't be doing that again. That was a cost-saving exercise. Every actor we could, we saved.
"I would only do it to save cost. I wouldn't do it because a) I don't think I'm any good and b) because you spend all day sitting around on set.
"It's interminable. I don't know how they do it actually. Nothing made me want to write more than acting for a day."