"I don't think organisations like Love Music Hate Racism "control" the events that are held under their banner as such, but there ought to be some uniformity of message"

It could be worth considering that at a Love Music Hate Racism event, like the old Anti Nazi League carnivals, its about using agreeable bands (most of them) to attract people to show solidarity against racism.

The uniformity of message is the FAF manifesto and the bands get people along to listen.

In the case of FAF you have the extra point of reclaiming english folk from the nazi's, but does there have to be a unity of message in terms of performance content?

Is that even what you meant?