On Darren Ferguson's 38th birthday, North End bounced back from two straight defeats to see off playoff chasing Sheffield United.
Preston had the lead early on when debutant Matty James, in front of Sir Alex Ferguson, found the net from the edge of the area.
Danny Welbeck, who played in his United teammate James, was also instrumental in North End's 2nd. The pacey forward was brought down in the box leaving the referee with no choice but to point to the spot.
Parkin saw his effort saved by Ian Bennett...
...but was on hand to tap home the rebound.
For more pictures from Tuesday's win over the Blades or indeed any other North End game, click here.