The document was written a week after the Feast of All Saints. Here is the Latin and the translation from the National Archives:
Ph[ilippus] dei gra[tia] Franc[orum] Rex dil[ec]tis et fidelib[us] gentib[us] n[ost]ris ad Roman[am] Cur[iam] destinatis, s[a]l[u]t[em] et dil[ectionem]. Mandam[us] vob[is] quat[enus] Sum[m]um Pontificem requiratis ut dilectum n[ost]r[u]m Guill[el]m[um] le Walois de Scotia militem reco[m]mendatum habeat in hiis q[ue] ap[ud] eum habu[er]it expedire. Dat[um] ap[ud] Petrafontem die Lun[e] post festum Omn[ium] Sanctor[um]. [Endorsed]: Quarta l[itte]ra R[egis] Franc[ie].
Philip by the grace of God, king of the French, to his beloved and loyal people appointed at the Roman Court, greetings and favour. We command you that you ask the Supreme Pontiff to consider with favour our beloved William le Wallace of Scotland, knight, with regard to those things which concern him that he has to expedite. Dated at Pierrefonds on the Monday after the feast of All Saints [7 November 1300]. [Endorsed]: Fourth letter of the King of France.
Billy here is a friend of ours from the other side
and he and his associates can help us with our English “problem”.
I consulted the perpetual calendar in The World Almanac and November 1, 1300, was on a Tuesday, so they have the date November 7 right. The journalist who reported on the story obviously did not know that November 1 is the feast of All Saints and misinterpreted the translation to mean that 7 November was the feast rather than the Monday after the feast.
If All Saints’ is observed with an Octave, which I would bet on at the time, then the Monday after the day is another way of saying the Monday within the Octave. If one’s life revolves around the liturgical calendar, this would be a very good way of identifying a day.