Had a little chuckle to myself on Friday, was on M25 about 1500 and there was a bit of a queue just before the A1 junction. A white 3 series BMW was weaving about the lanes to get a few feet ahead, even went down the exit then changed his mind and cut across all four lanes then back across to inside lane of the on slip, off he went into the distance then a mile later I saw him pulling onto hard shoulder along with a truck that I assume had hit him as his rear offside bumper looked a bit mangled. I hope artic driver had a dashcam.
I suppose you stopped and gave the lorry driver your phone number etc.