Contestants were given advice on diet and keeping fit, but, said Miss Sinclair, keeping things in perspective has been just as important.
"If you're a girl, there's always pressure to be thinner," she said. "But in this industry you've got to be happy with the person you are."
She is the latest teenager from Pinner to create a sensation. In 1992, 18-year-old actress Jane March became known as the "Sinner from Pinner" when she appeared in an explicit French film.