Chanel Cocktail Black Flapper Dress in 1926.  Coco Chanel originated the concept of the "little  black dress" which with the addition of certain accessories could be worn for evening cocktail hours.

Edward Steichen, Marion Morehouse in crepe romain dress by Chanel, 1926 © Condé Nast Archive/Corbis.

Staying in Vogue in the Roaring 20s:

Vintage Style…Royal Ascot fashion a living proof of an immortal style. One could wear this outfit to Royal Ascot at present and hit the best dressed list time and time again.

Joan Crawford as  Joslyn Poe in 'The Taxi Dancer' 1927

Flapper Style Joan Crawford as 'Joslyn Poe' - 1927 - The Taxi Dancer - Costume Design by André-ani (uncredited) - Director: Harry F.

1920's fashion. So glamorous!

The original poster indicated this was "Lily" and the tags that she was a British actress. -- Such an elegant style, uugh why can't society have this level of class?