Some have said that the second car was following too closely, it is more likely that the gap had closed as the front car was slowing to pull into the laybay. A scenario that no doubt we have all been party too, following at a safe distance, the car in front indicates a turn, you lift off and try to avoid loss of momentum figuring that by the time you reach the preceding vehicle your path is clear and you can accellerate again. No brake lights shown, so Mr impatient behind thinks I'll pass him, not realising what's going on ahead. Too often people only look at the car in front not the several cars that may be ahead. Driver awareness again!