They are the dresses that put other glistening leading ladies in the shade, the surprising, exclusive gowns that made sure last year's Oscar ceremony would live on in the memory.

When Kate Winslet stepped out of her limo to face the massed ranks of Hollywood photographers, her startling, vermillion dress with its distinctive shoulder garland marked her out as one of the brightest stars of the evening. Now the original design for that famous Ben de Lisi gown is to go under the hammer, along with a selection of rival couturiers' sketches for several of the most striking outfits worn that night.

Oscar-winner Halle Berry, who received the Academy Award for best actress in recognition of her performance in Monster's Ball , is probably as much remembered for the unusual, embroidered net bodice she wore to collect her statuette as she is for the accolade itself. Her dress, by the unknown Lebanese designer Elie Saab, was so flatteringly different that in just a few hours it established Saab as a new Hollywood favourite. Like the De Lisi sketch, Saab's drawing is signed by both the designer and the film star.

The artwork of the two designers has been donated to a London charity auction to be held this month at Planet Hollywood in aid of two British children's charities. The sketches are expected to fetch five-figure sums.

Also available will be the sketch for Donatella Versace's daring, satin creation for Jennifer Lopez, worn to interesting effect with a bouffant retro hairstyle. The gold John Galliano dress worn by Nicole Kidman at the Oscars two years previously will also be on sale, as will the Valentino design for Gwyneth Paltrow's outfit at the Venice film festival.

The sketch for Britney Spears's much-photographed asymmetric, silver halter-neck shift, worn for the premiere of the film Crossroads , will be on sale too.