Haha. One of the forum's biggest cliches that one, isn't it?
I'm going to be a bit controversial here. I think the crowd is overstated for that game. The stadium was full to capacity, no doubt, but the away end which held a few thousand was practically empty, and the bit in front of the away end wasn't as packed as the rest of the kippax. I know because I climbed over the fence to get in that bit to escape the crush.
When we used to get 52,000 in the 70s and 80s there were always a capacity 6 or 7000 away fans in that section. With charlton only bringing a couple of hundred the stadium was full to capacity or even more.