Its easy to see why Hort's theory of an imposed Latin insertion was popular among extreme anti-Papal Protestants. Yet the full evidence concerning the history of the verses cannot really be dismissed so simply. The passage is actually found to have been popular all over the Empire at least before 400 A.D.

The REAL Spread of the Pericope de Adultera

And its apparent origin appears to be in the Far East according to Eusebius, not the West. The first explicit notice of the passage is given by Papias around 120 A.D. in the middle of Turkey. As Hort himself notes further on:
"[Eusebius] closes his account of the work of Papias (Cent. II) with the words "And he has likewise set forth another narrative (istorian) concerning a woman who was maliciously accused before the Lord touching many sins (epi pollaiV amartiaiV diablhqeishV epi tou kuriou), which is contained in the Gospel according to the Hebrews". (Hort, Introd., Appendix I. Notes on Select Readings, pg 83) Hort had no doubts over the identity of our passage here, and few others do either. The only real questions remaining concern the reliability of both early fathers as to some curious details in this report.
Papias is independantly confirmed as "a hearer of John and companion to Polycarp" by Irenaeus. He apparently lived from about 60-135 A.D. Eusebius calls him 'bishop of Hierapolis' (the modern town of Pamukkale, in Turkey near Colossae) but little else is known. Although Eusebius scorns him as "a man of small mental capacity", this is apparently because Eusebius himself interpreted the Gospels allegorically, while Papias believed in their literal truth.