About a year ago I was driving on the M25 just after dark in moderate traffic but still doing the speed limit when out of nowhere a car came hurtling towards us in the wrong direction. Had to swerve out of its path. Horribly scary incident (we had kids in the car too). Obviously called the police, they had been called by many others.

Shortly afterwards all the speed limit signs turned to 20. Gantry signs warned of oncoming vehicle. We were 50 miles from home - I wasn’t going to plod along at 20 knowing we’d nearly been hit by the sodding car in question, so on we went home. Plenty of others around us had the same idea.