Born in Hamburg, Germany, son of a British father and German mother, Brandt grew up during World War I, during which his father, who had lived in Germany since the age of five, was interned for six months by the Germans as a British citizen. Brandt later disowned his German heritage and would claim he was born in South London. Shortly after the war, he contracted tuberculosis and spent much of his youth in a sanatorium in Davos, Switzerland. He traveled to Vienna to undertake a course of treatment by psychoanalysis. He was, in any case, pronounced cured and was taken under the wing of socialite Eugenie Schwarzwald. When Ezra Pound visited the Schwarzwald residence, Brandt made his portrait. In appreciation, Pound allegedly offered Brandt an introduction to Man Ray, whose Paris studio and darkroom Brandt would access in 1930.