I'm surprised that a "non-runner" can beat 4:24. How exactly does that work, or is the O'Brien family just gifted?
It's an out-and-back course. I have my suspicions. I never saw him overtake, and my dad didn't see him pass him on the return. 4:24 is certainly slow for me, it's the slowest of the 70-odd parkruns I've done, and Edinburgh is one of the fastest parkrun courses.