Since I'm talking about Robin Hood anyway, perhaps I should throw in some other date pegs.

The "Gest of Robyn Hode" is the earliest extant Robin Hood romance to contain the motif of The King and the Subject, in which Robin is reconciled with the King.

The king is named "Edward." This is unequivocal. We read about "Edward our comely king" in stanza 353, and "Edward, our king" in stanzas 384 and 450. All these readings are unequivocal; the witnesses to these lines all read "Edward." (Admittedly there is really only one witness to the texts of these stanzas, Wynken de Worde's print; all the others are descended from it.)

There were several pre-Conquest Kings Edward, but no pre-conquest outlaw would be named Robin. So we must look to the post-conquest Edwards: Edward I (reigned 1272-1307), Edward II (1307-1327), Edward III (1327-1377), Edward IV (1461-1470 and 1471-1483).

Once again we get an earliest possible date in the thirteenth century.

There is one other dating hint of significance: In stanza 91, the abbot swears "By God and Saint Richard" (spelled "Rycharde" in the print). No scholar has ever found a "Saint Richard." I have solved this: Saint Richard is Richard Scrope, Archbishop of York, executed 1405 by Henry IV. Scrope was never canonized, because Henry made sure he was never canonized, but the people of northern England attributed miracles to him; informally, he was clearly regarded as a saint.

This doesn't really date the Robin Hood legend, but it does date the redaction date of the published version "Gest" -- to probably the first third of the fifteenth century. That almost certainly makes the reference an anachronism. But the extant early sources (the ones the pop depictions of Robin Hood ignore) are most definitely converging on a date in the thirteenth or fourteenth century, with the latter the more likely. The "Gest" on a number of grounds best fits the reign of Edward II.