Lady Britomart Undershaft was modelled on Rosalind Howard, Countess of Carlisle, the mother-in-law of Gilbert Murray, who with his wife Lady Mary served as inspiration for Adolphus Cusins and Barbara Undershaft.
Andrew Undershaft was loosely inspired by a number of figures, including the arms dealer Basil Zaharoff, and German armanents family Krupp. Undershaft's unscrupulous sale of weapons to any and all bidders, as well as his government influence and more pertinently his company's method of succession (to a foundling rather than a son), tie him especially to Krupp steel. Friedrich Alfred Krupp died by suicide in 1902 following publication of claims he was a homosexual. His two daughters were his heirs. Undershaft shares a name with a Church of England church in the City of London named St Andrew Undershaft; given the City's longstanding status as the financial center of London, the association underscores the play's thematic emphasis on the interpenetration of religion and economics, faith and capital. Undershaft's morality can be compared to the philosophy of Friedrich Nietzsche.