The dress worn by Audrey Hepburn on the night she won her best actress Oscar is expected to fetch up to £60,000 at an auction later this month, auctioneers have said.
The ivory lace gown was designed to be worn for her role starring alongside Gregory Peck in the 1953 romantic comedy Roman Holiday.
It was later adapted for Hepburn to collect the Academy Award for Best Actress in 1954 for the same film.
Her changes meant the dress cut straight across at the front and plunged low at the back. She added spaghetti straps, thought to be inspired by Hubert de Givenchy, who by 1954 had become her costume designer.
She cut her hair in short, pixie style to collect the award.
After the ceremony, it was not known what happened to the dress, made by costume designer Edith Head.
In fact, Hepburn gave it to her mother, Ella van Heemstra, who passed it on to a friend living in America. The friend's family have kept it ever since in a box in the bottom of a wardrobe.
The Breakfast At Tiffany's actress, who died in 1993 aged 63, told her mother it was her "lucky dress".
The auction is scheduled to be held by Kerry Taylor Auctions on Tuesday November 29 at La Galleria on Pall Mall, London. The firm is hoping to repeat the success of its 2009 auction of items from Hepburn's collection. It estimates that the dress will go for between £40,000 and £60,000.
Kate Osborn, an assistant at the company, said: "There are a few people who just love Audrey and collect all of her pieces, so I'm sure they'll want to bid, and maybe museums as well."