James Montgomery, in an early footnote in his 1923 book The Origin of the Gospel According to St John:

I may have academically “declassed” myself by using the name “Gospel of St John” in the title. … I frankly think that “Fourth Gospel” is a scholastic affectation. Why not the First, Second, and Third Gospels? Are we any surer of their authors? Any tyro knows that Deuteronomy is not “the Second Giving of the Law,” but are we obliged to make constant profession of our critical attainments by calling that document the Fifth Book of Pseudo-Moses?

(I discovered this quote in another footnote—on page 4 of John A. T. Robinson’s 1985 The Priority of John.)