It was a car and trailer apparently car turned over, pictures show trailer on its side, according to Manchester newspaper horse out and walking OK. Sounds like a good result.
Same happened on the A303 on Sunday but no injuries to the horse (that I heard of).
Also when travelling around the north m25 on Sunday there was a broken down horse box on the side of the road. Hope they were all OK. Did wonder if they’d come from the London Horse show.