In an interview Metro Cafe, Celia Imrie, who played fighter pilot Bravo 5 in Episode I, talks about how she got the Star Wars role:

It was a surprise to see you in Star Wars: The Phantom Menace. How did that come about?
I'm amazed anyone recognised me covered up in that hat and goggles. The casting director had seen me in a Harold Pinter play and asked me to be in Star Wars - how bizarre is that? I think I was originally up for the part of the mother at the beginning of the film but, when I didn't get it, they asked me to be a fighter pilot instead. I can't pretend I was a life-long Star Wars fan but I did think it would be rather cool for my son if his mum was in the film. He was little at the time so, when we went to see it, he went to sleep and missed me, but he got to see it with his school friends later. None of us knew what the story was, though. Because the producers are so worried about leaks, we had no idea how we fitted into the film. It was just terribly exciting to be on the set and part of a phenomenon like Star Wars.

Thanks to Simon for the alert.