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But otherwise it's ok, Spath? ;o) I believe the term used by the motoring organisations is called "Waving", where people travel too quickly, then have to brake to avoid a collision, which causes those behind to brake and eventually come to a stop.
237SJ - I'll give the M25 a miss. I've only ever driven on it once. It was a Saturday morning and fairly quiet so I didn't have any problems. But I hear too much bad news about the traffic on there. It's the same as all the roads in this country - they weren't built for motor vehicles, just horse and cart.