Dali's 1943 "Portrait of Mrs. Harrison Williams" will go under the hammer Tuesday with an estimated price of between 1.5 million and 2 million pounds ($2.4 million and $3.2 million).
Dali painted the ultra-rich and super-stylish socialite—who later became Countess Mona Bismarck—barefoot and dressed in black rags.
Proceeds will go to the Mona Bismarck American Center in Paris, which promotes Franco-American cultural relations.
Also for sale is Miro's 1936 "The Farmer and His Wife," a vibrant portrait of human figures and barnyard animals, valued between 5.5 million pounds and 7.5 million pounds ($8.7 million to $11.9 million).
Reporters also were given a preview Thursday of Sotheby's February auctions of Impressionist, modern and contemporary art, including works by Pablo Picasso, Claude Monet, Egon Schiele, Francis Bacon and Jean-Michel Basquiat.