One thing there was which, it was clearly understood from the outset, could not be done at all during the King’s minority. No grant in perpetuity made by, or in the name of, a person under age was valid by English law. The application of this rule to the case of an infant King seems not to have been expressed till more than two years after Henry’s coronation, but it was effectually secured during that time by an expedient whose simplicity and practicality are eminently characteristic of the Marshal. A grant in perpetuity on the part of the Crown was invalid unless sealed with the King’s seal. No great seal was made for Henry till two years after he was crowned; the seal of the regent served in its stead.[360] On several occasions during the first year of the regency grants were made in the King’s name to hold good “till the fourteenth completed year of our age.”[361] {1216–1217} There was as yet no fixed rule for the determination of a King’s majority; but the reigning King of France, Philip Augustus, had been crowned as his father’s colleague shortly after his fourteenth birthday, and had exercised the functions of royalty from that time forth. This was the origin of the rule which fixed the coming of age of later Kings of France at fourteen years; and Henry’s guardians seem at first to have contemplated taking Philip’s case as a precedent for that of their own boy-sovereign.[362] There was no English precedent to guide them. Nine years later it was asserted that one castellan--Peter de Maulay--had bound himself by an oath to John not to give back the castles of which he had charge till Henry should be of legal age.[363] It is possible that John may have demanded and received such an oath from more than one of the wardens of the royal castles; but evidently neither they, the Marshal, nor any of the council knew what was John’s idea--if he even had one--of what should constitute legal age in the case of his successor; the definition tentatively suggested at the beginning of the reign was clearly not based upon any direction left by him. At the close of 1217 it was abandoned, and its place was taken by a vaguer formula--“till our coming of age.”[364] The question of when that was to be could not become urgent for three years at least; it was therefore wisely put aside for solution at a more convenient season. [Sidenote: 1215–1216]