Well, after this morning's off... was riding home and came across a fellow rider on the ground at the three lane stretch of the A406 just before Hanger Lane going South.
I blocked the lane he was straddling (he was in lane one but into lane 2) with my bike's hazards on. Datatool 3 does have some benefits (hazard function) and kept him chipper till the blues and twos arrived.
Nice to pass on the goodwill of the people that were great helping me out.
He'd been swiped while filtering - never fun. Seemed not too bad, broken ankle at worst, seemed like a bad sprain,