"What's the betting she didn't walk to LHR ?"
Unfortunately they picked up on the concept of irony and an instruction was given to all the soap-dodging treehuggers by Swampy Control notto fly. The ones from Leeds went by train or Happy Bus I think (thereby pumping CO2 into the environment anyway). Our local protestor turns up in a minibus whenever she wants to glue herself to the terminal door.
I don't know if they are in the field illegally; it might be that they have permission from the landowner in which case they are not committing an offence (till they actually find one to commit).