I think it was a league game against Spurs in their double season - the crowd certainly broke those gates that day. There were also people walking along the roof of the popular side and sitting along the ridge - god knows how no-one went through the asbestos sheeting!
We usually went in the pop then, but when we arrived (about an hour early) the police were already directing people away from there to the kop. We got in OK and stood abour 1/3 of the way along. gradually we got pushed further until we were behind the goal, where the pressure from both ends kept increasing - there were no pens or gangways then, just a continuous terrace with a few crush rails. We had just got ourselves in front of one of them when the whole crowd rocked as if a tidal wave had hit it - that was when the gates went down. My mate got his fags out (a majority were smokers then) and found his arm was trapped up in the air holding the packet. Looking round you could see others in the same plight - rather surreal, dozens of arms raised holding fag packets! The crush gradually eased a bit as the game got started and people shuffled round, but it must have taken over half an hour to get out at the end, which is when we saw what had happened to the gates.
I shudder to think now what might have happened, but at the time it was just a big laugh, and everyone remained remarkably good humoured. I'd love to see some of that atmosphere back, but not the dangerous conditions.