Sir Thomas Gresham ( c. 1519 -- 21 November , 1579 ) was an English merchant who worked for King Edward VI of England and for Edward 's half-sister Queen Elizabeth I of England . Sir Thomas Gresham ( nÃ e Thomas Gresham Levieux c. 1519 â `` 21 November 1579 ) was an English merchant and financier who worked for King Edward VI of England and for Edward 's half-sisters , Queens Mary I and Elizabeth I.