The burly winger ran on after just five minutes when an accidental clash of heads ended Martyn Harvey’s game.
Harvey’s top lip was split apart in the encounter and he needed stitches to mend the deep wound.
Tilley crossed for Towcester’s first moments after coming on when he finished a rampaging run by in form No 8 Craig Holton.
Holton bagged a score of his own minutes later before Tilley raced in for two more tries in quick succession to complete his lightening hattrick.
With score at 24-0, a rout looked on the cards but Park dug in and hit back through a darting run by their centre who prised open the midfield to score.
The visitors’ fly-half added the conversion and two penalties and the two sides turned round with the scores standing at 24-13.
If the first half belonged to Tilley, the second belonged to full back Matt Yuill, who also bagged a hattrick, his third of the season.
Yuill’s first came two minutes into the second half and the score settled the nerves of the vice-presidents crowd.
Next on the try-scoring list were Joe ‘Cake’ Chambers, who had also just come off the subs bench, flanker Eugene Baxter and Holton for his second.
Looking sublime with ball in hand, Yuill carved through Stockwood Park defence twice more and finished the day with 27 points to his name.
The win continues Tows’ unbeaten run in the League and next week they make the all-important trip to title rivals Peterborough Lions.
Milton Keynes II 8 Towcester II 26
Alan Chapman, Adam Wilkinson, Ben Lawrence and Jamie Cartwright scored the tries and Brandon Kerr added three conversions.
Photos from the Stockwood Park game are available here:
http://www.flickr.com/photos/towcesternews/sets/72157626202019434/with/5499813445/
Please credit James Rudd AboutMyArea.co.uk/nn12