h2g2 The Hitchhiker's Guide to the Galaxy: Earth Edition

Thank you to Ginger for confirming my thoughts about the residents of the Bristol area, but they've been at it again! A 15 mile tail back on the M5, which will keep most of its victims in 90 degree heat all day! What I want to know is who was at the front of the queue and why were they driving so slowly? Was it someone from outside Bristol, say Cheltenham or Wales getting their own back in some age old feud, or perhaps someone looking for a turn? And why didn't everyone just drive around them in the two other available lanes? Anyone who can answer these questions, or was close enough to the front of the queue to get a description of the car please enlighten me!