Karoly Hajdu (1920–1981), better-known as Charlotte Bach, was a Hungarian-British impostor who later in life became a trans woman and fringe evolutionary theorist. She developed an alternative theory of evolution which acquired a cult following among prominent writers and scientists in the London of the 1970s, who remained ignorant of her original identity until after her death. Early life Hajdu was born near Budapest in 1920. In the wake of World War II she moved to England and in 1948 began to use the name Baron Carl Hajdu. In 1956 she collected money for Hungarian freedom fighters resisting the then Soviet occupation. The People, which specialised in lurid exposés, alleged that Hajdu had pocketed the proceeds. She was found guilty of fraud in 1957, and was forced into bankruptcy. Hajdu then adopted the persona of writer and society hypnotherapist Michel Karoly. She rented an apartment in Mayfair. She began to acquire a following in polite society, and wrote an advice column in a mass-selling magazine of the day. Karoly continued in this role until 1965, when both her wife and stepson suddenly died. She was declared bankrupt again, and in 1966 was sentenced to two months in gaol for acquiring a loan whilst bankrupt. By her own account, the sudden deaths had precipitated a profound identity crisis. Life as a woman In 1968, Hajdu adopted the new identity of Dr Charlotte Bach, a supposed former lecturer at Budapest's Eötvös Loránd University, whose alumni included the philosophers Michael and Karl Polanyi and the mathematician John von Neumann. 'Dr Bach' would openly tell lecture audiences how at first, putting ads in the windows of local newsagents, she had worked as a dominatrix. This experience had provided invaluable research data, she said, for the purpose of compiling a dictionary of psychology. These researches had in turn led to the all-embracing theory. She lived full-time as Charlotte Bach until she died. She was thus what is sometimes referred to as a non-op trans woman. Human ethology In 1971 Bach unveiled her transformative, as she would insist, theory of evolution. Among other things, she argued, it correctly displaced Darwinism in favour of Lamarckism. Drawing heavily on the work of animal ethologists such as Tinbergen and Konrad Lorenz, she argued that humans experience in varying degrees a pull towards becoming the opposite sex. This urge could either be denied or asseverated: gays and femme lesbians, for