The Chester Beatty papyrus codex of the Four Gospels and Acts (P 45 in the official list of New Testament papyri), usually considered to have been written about the middle of the 3rd century A.D., is still the earliest surviving manuscript to contain all four gospels, and as such is a unique monument of early Christian literature and a treasure of the Irish nation.–T. C. Skeat, "A Codicological Analysis of the Chester Beatty Papyrus Codex of Gospels and Acts (P 45)," now in The Collected Biblical Writings of T. C. Skeat, 141.
The Chester Beatty Codex of the Gospels and Acts (P45) was a find of sensational importance for the textual history of the New Testament. Like a flare bursting over a night time battlefield, it cast light upon the previously darkened pre-Constantinian centuries of the textual history of the New Testament, forcing revisions of scholarly views on several major matters. In one giant step, P45 brought scholarship on the text of the Gospels from the mid-fourth century practically to the doorstep of the second century. First made available to the scholarly world in the 1933 edition by Frederic G. Kenyon, for New Testament scholars P45 is the jewel in the crown of the 12 Greek biblical manuscripts acquired by Alfred Chester Beatty about 1930.–Larry Hurtado, "P45 and the Textual History of the Gospel of Mark," in The Earliest Gospels: The Origins and Transmission of the Earliest Christian Gospels--The Contribution of the Chester Beatty Gospel Codex P45, 132.