Thanks, team. We were only about 50 yards apart and could both see the buck - sometimes. He shot when I couldn't see it and, as it rushed past me, I thought it had just spooked. But it suddenly stopped, wobbled, and fell over - now out of my son's field of view. Definitely an easy retrieval.
This morning we had our first frost and I expected lots of activity, but there was as little as I've seen so far. Perhaps better tomorrow.