Her catwalk debut reportedly marked the first time her husband-to-be Prince William first saw the attractive brunette, reports Contactmusic.
Middleton wore the Charlotte Todd knitted slip at a St. Andrews University charity fashion show.
Todd, who now works in an aquarium, has kept the outfit ever since it was returned to her.
The dress will be sold at a Kerry Taylor Auctions sale in March (2011).
"It's definitely a showstopping dress. I'd like to think I played my part in history and in fashion history," Todd said.
