Grammar and Hardy

From Way Out West (dir. James W. Horne, 1937). Lottie Hardy (Mae Busch) to Betty Laurel (Dorothy Christy): “If I didn’t know that Oliver was in Honolulu, I’d swear that was he on the phone.”

Take a look at the fortunes of “that was he” and “that was him” in American English via the Google Ngram Viewer. The fortunes of “that was she” and “that was her” are another story.

[Unlike “that was he” and “that was him,” “that was her” can be followed by a noun: “that was her mother on the phone.” But the history of “that was she” is still pretty telling.]