This paper examines the story of Mark Weston, a successful competitor in women's track and field who in 1936 underwent a so‐called 'sex change' or 'metamorphosis' to manhood. Shortly after news about this metamorphosis became public, it was recommended that 'physical examinations' be instituted in women's sport to ensure that women athletes were 100 _I_per cent_i_ female. This was a precursor of 'gender verification' policies in sport, which have aimed to ascertain that women athletes are 'female enough' to compete as women. Weston's metamorphosis story is, however, missing from most histories of gender verification. When included, Weston has been labelled 'transgender'/'transsexual', even though these labels were not used by his contemporaries. This paper argues that placing Weston's story at the centre of gender verification's history offers a way to conceptualise differently both the past and present of gender verification and the relationship between past and present manifestations of gender variance in sport. [ABSTRACT FROM AUTHOR]