During the sixties when every RAF station was inundated with ban the bomb protesters, we would bring out the crash tenders and point the nozzles at the fences. A senior RAF officer with megaphone in hand would explain that these vehicles created foam and were used on aircraft fires. he further explained that the foam was made using ox blood and water and once on their clothes it was impossible to remove and it stank to high heaven. Nobody wanted to climb the fences after that. The police here should use the tactic, tell the protesters they were entitled to glue themselves to the road but nobody would help to remove them.