Re the crowd, I had bought my ticket online and was on the way down when I got caught up in the delays on the A12.
After nearly 3 hours, most of it not moving, I reckoned I wouldn't get there till 8.30 so I abandoned the attempt and went home.
Given there were bad jams on the M11 and M25 as well, due to the M11 closure, maybe others didn't make it either?