Black's position had been slightly better for a while, but after the mistake committed a couple of moves back, his king got under fire. Now White can win quickly by 62.Qd8+ Kxe6 63.Qe8+ Kf6 64.Rf7# or 62...Ke5 63.Ra5. Yet, the move made by Ian does not spoil much, as the computer gives it the evaluation of +10 as well.
62.Rf7+ Ke5 63.e7 Nxe7 64.Rxe7+ Kd4 65.Qa1+ Kc4 66.Qc1+. This check looks better if 66.Rc7! Qxc7 is included.
White kept pushing the black king around, but failed to deliver mate, and then, upon missing a very subtle winning opportunity on the move 80, suddenly found himself under a very unpleasant check.