Of course, he might have been slotted into the post on a temporary basis as the best-qualified member of the existing staff when a previous head departed abruptly. But this seems unlikely. Justin’s foundation post suggests that he was head for some years, and normally proceedings to appoint a new permanent head would not be delayed for more than a few months in the event of a temporary headship arising. Of course, it could be that the school tried and failed to attract a permanent head, in which case a temporary head might have remained in post for the required period.