When the various anti-terrorism laws were set in place, the government promised everybody that these powers were to cope with a limited, awful problem. Some idiots believed it. Perhaps one of them (though I doubt it), was Chris Kitchen, an environmentalist activist.
Amongst those with other ideas were the police, who realised that the Terrorism Act 2000 could be used to harass and obstruct anyone with whom they have an ideological disagreement. They don't need to go about the hassle of charging, court appearances, juries and all the other checks and balances which attend the prosecution of justice in a democracy.
Mr. Kitchen was on the bus to Denmark when he was hauled off it under the Terrorism Act to see whether he was a terrorist. On protesting that environmentalism isn't terrorism, the officer informed him that 'terrorism means a lot of things' - which a) isn't true and b) demonstrates the inevitable creeping use of oppressive laws to stifle citizens' freedom of movement and expression.
Sure, it's an isolated case - so far. A fair few hundred people are heading to Copenhagen, and they're not terrorists, just people who want to remind those in the motorcades and fancy hotels that more than just votes are at stake. Time for the police to remember that their duty is to the public, not to those with whom they agree.