La Voix, who will play Wishee Washee in Aladdin coming later in the year, plays a club singer in the film released on Friday.
And it was a dream come true for the star that happened in a flash.
She said: “There was no audition, no meetings, just that Jennifer Saunders had seen me on Britain’s Got Talent and asked me to be in it.
“I just had to say yes. The next day I was recording the backing vocals and then two weeks later, we were filming. It was a whirlwind.”
She plays a nightclub singer where Saffy goes to track down both Edina and Patsy who are on the run after killing Kate Moss.
And she was full of praise for the stars of the show.
La Voix said: “It was unbelievable that we were there. You see Jennifer Saunders, Joanna Lumley and Julia Sawalha, it was wonderful.
“It was Jennifer’s film but she did give us a free reign if we came up with ideas to do things a different way.
“It was like a little family and I suspect it’ll be one of the highlights for the rest of my career.”
And La Voix is also looking forward to returning to Aylesbury.
She said: “I did the first pantomime at the Waterside with Cilla Black and can’t wait to go back.
“I have such good memories of working on that show. Normally I play the Ugly Sisters so it will be nice to get some cheers, I hope, as Wishee Washee.”