Wx at the accident scene - must be surmise on my part. I had driven 8 miles or so in the opposite direction at 2130 with no significant variation in the 30-40m vis so think it unlikely it would have been different a mile away at the Hall. The hall is on a slight rise I guess 50 ft above sea level max, my place is 30 ft. Wind calm. Light - none. very dark despite a full moon. When I was looking for the circling helos at 2100 - 2130 the moon was occasionally visible for an instant as a dim disk. The helos were not visible, nor were any lights on them.
True, this was a couple of hours after the accident so I can't be sure what things were like at 1930. As I drove to the pub at 1840 it was dusk with mist forming fast at ground level and vis I'd estimate at 2-3000m and reducing quickly. It would have been dark by 1930.