Update from the PH thread...
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.