I can confirm the following, as I've just spoken to the driver (who's a good mate of mine - none of this mate-of-a-mate stuff here)...
He (just to confirm: male, brown hair) blacked out. He remembers commenting to his two passengers on how hot it was, and the last thing he remembers was turning the air-con up. Then he woke to find a paramedic putting a neck-brace on him! I have no idea how much water he drank, but he's generally got a bottle of water with him when he needs it, so I don't think we can blame him for that.
He is a Honda employee, by the way. And not only will he be getting loads of stick from his work colleagues, but from me and the rest of his mates for a very long time to come. Blokes shouldn't faint, and he knows this.
So well done and thanks to everyone who gave him the benefit of the doubt and well-wished him and everyone else involved. And sod off to the usual bunch of forum morons that are always so quick to judge without even the slightest bit of knowledge.
Greg - enjoy your pie
