I'd read somewhere on the web that the issue was one of curfew and (possibly) public transport. The account was from a stage tech. Grand Funk were going down very well. So well that their manager tried to keep things going (he had quite an interest). So did Grant and Co. They would get fined (and I think, did) and had visas etc to consider. So apparently the power was cut as Grand Funk went over time and then Zeppelin played resulting in going over time as well. Pitting Grant against the Funk manager and making an issue out of height and build etc merely creates false equivalency. Even now there is a lot of emotion; rock fans going out of their mind are not going to understand the the reason and certainly not when the "we blew Zeppelin off stage" narrative is repeated but unsupported by all the facts. Grand Funk did capitalize on the event. Did not read of Zeppelin taking an hour and a half between sets though . More grist to rock politics fire. First casualty facts.