Here is a short time-lapse of fans leaving Wembley Stadium after Brazil played England in an international friendly on February 6, 2012. I was positioned on a bridge over the walkway in front of the Wembley Park tube station. The police use the horses to regulate the flow of people in to the tub station, so the platforms do not become dangerously crowded.
The match was obviously a sold out stadium of 90,000. The time-lapse begins about 20 minutes after the fans started leaving and about an hour elapses in it, so this is approximately 75% of the fans that left in this direction. A police officer told me that the space from the horses to the first black pole will have approximately 2,000-2,500 people when they are stopped.
5D Mark II
16-35mm @ 35mm f/8
1 second shutter