I know someone who was at the scene of the accident calling for an ambulance (assuming it's the same accident, but based on the date, location and story, I'm 99% sure). I was not there personally but this is what I was told:
The accident involved 3 people and it was late at night: The Brit was not riding a motorbike, but he was a passenger on one which was being ridden by a local lady. The lady merged onto the oncoming traffic lane to ride the wrong way to avoid having to U-turn much further away (there is a raised lane divider on this part of the road, with a U-turn further up). However, there was a local man riding at a decent speed from the other direction, correctly in his lane, who hit the lady + Brit crossing the road. The Brit passenger and the Thai man got injured and the lady who caused the mess was mostly uninjured.
Very nasty accident. If everything happened as described, can't really blame anyone except the lady taking the shortcut out of laziness, which ultimately caused life-changing injuries for the Brit and possibly for the Thai guy as well. The moral of the story: never ride as a passenger on a motorbike and let someone else be in control of your life.