It seems that the person ordained as P is the same as the one ordained D, as there is no other Matthew Mead in Foster. But, assuming that this link is right, it is odd that Foster does not pick up his move to Hart Hall.
Foster: Mead, Matthew, s. Rich., of Brickhill, Bucks., pleb. Wadham Coll., matric. 2 May 1679, aged 15; BA 25 Jan 1682-3, MA 1685, chaplain 1689, incorporated at Cambridge 1711. See Rawl., vi. 129; Gardiner, 324.