Before the start:

Sandeep's photo of me before the start.
It was cold - a longer warmup would have been good. And it poured with rain at one stage (around Scrivener) during the run.
I caught Sandeep at about 7k and ran with him for a few kilometres, then kept him in sight. I am please to report he broke the 80 minute barrier.
Experiment successful - the feet and legs are fine.