But I would like an explanation of why, coming out on to the A10 this morning, I was to witness one tractor doing a U-turn around the roundabout at the end of our street. And why, my having followed said tractor the kilometre out to the leisure centre roundabout near the A505 bypass, it then did another U-turn to head back into town again.
(I was tempted to stay and see whether it just kept shuttling back and forth along the A10 between the two roundabouts, but I had to get to work.)
ETA: it looks like
jon_a_five and silly_swordsman have it between them: there's a tractor dealer down a side road halfway between the two roundabouts, so someone doing a quick road test matches the path. 