"If this side [verso] did originally contain the commencement of Matthew, it would certainly be suitable since, as stated above, Matthew appears to have begun on the inside (cols. 3 and 4) of a leaf. But we should then have to assume that the whole of the original writing had been effaced, leaving no trace, which is very unlikely. The probability is therefore that the fragment comes from a fly-leaf at the beginning of the manuscripts" ("The Oldest Manuscript of the Four Gospels?" NTS 43 : 1-34, here 18).
Skeat is probably correct, given the absence of writing on the verso, that this is a cover sheet or flyleaf. On page 217 Gathercole states, "There are parallels to this sort of single-sided title flyleaf, such as the first page of P62" and he cites here the edition of P62 by Leiv Amundsen. But when I looked at Amundsen, I found that this does not seem to be the case. P62 (P.Osl. inv. 1661) does contain a flyleaf, but it is (as opposed to Gathercole's papyrus) blank on the outside pages (recto, in this case) and contains a title on the inside (verso). It is misleading when Gathercole says that a title occurs on "the first page of P62," since page 1 of P62 is the outside blank page (see Amundsen, "Christian Papyri from the Oslo Collection," Symbolae Osloenses : 121 and 129). As Amundsen records on p. 129 of his edition, "Page 1. No text...Page 2, the title." The flyleaf of P62, then, cannot be understood as the same kind of flyleaf that we find in Gathercole's papyrus and so does not serve as a good "parallel" to that fragment. The beginning of Matthew in Gathercole's papyrus (assuming that some portion of the Gospel did indeed follow the title page!) would have begun on the recto of another sheet.
Besides this confusion, I thought Gathercole's article was very interesting and well researched. Gathercole hopes that this papyrus will be included in the Nestle-Aland hand edition and be cited either 1) as part of the codex of P4 or 2) given a new accession number in the papyri. I highly doubt, however, that the flyleaf discussed here will be sufficient evidence to support the view that it is part of the codex of P4, and I am certain that it will not be registered with Münster as a new papyrus, since it is not a continuous-text manuscript. But I think this is a very important papyrus fragment which attests to an early title of Matthew's Gospel and thus should not be ignored. In the very near future, I shall say a lot more about what I think should be done with respect to important non-continuous-text manuscripts of the NT, so stay tuned! For now, Gathercole is to be commended for his research on this widely neglected fragment.