Much disagreement to the origin of the source material exists. Some contemporary sources believed the source was Lytton Strachey's 1918 biographical essay in "Eminent Victorians". Others contend Michael Jacoby was the author. Warner Bros. executive Hal B. Wallis contended that the life of Florence Nightingale was in the public domain, and that screenwriter Mordaunt Shairp did his own research. The MPAA agreed with Wallis; no source credit was necessary.