Glad it seems no one was injured in that, could have been nasty.
A good number of years ago now we were driving south with the caravan,going over the Shap summit when we were overtaken by what looked like an older two berth van being towed along at a fair but not dangerous speed. Just as he was pulling back into the left lane I noticed the van's offside wheel starting to wobble a bit, caravan looked stable enough but that wheel didn't. Next thing I knew was the wheel was off, the caravan offside hub was against the road throwing up a sheet of orange sparks. The driver pulled over safely, no one hurt, people stopped to make sure the driver was ok. What really struck me (glad the wheel didn't) was the speed the loose wheel maintained when it came off. The wheel actually overtook the towing car, bouncing several times at what seemed a good old height before disappearing over the fence on the left and into the moor where it is probably still lying to this day. Would not have liked to have got in the way of that wheel either as a pedestrian or driver.