“Kettle” appears in the dictionary only as a noun, not a verb. So, the term “kettling” is not yet official. To determine why this word has acquired this meaning, let us look at the existing meaning of the word.
Well, a kettle is a container used to raise a liquid, usually water, to its boiling point. Based on that, it would be logical to conclude that a police kettle is intended to bring the contents, i.e. the protesters, to boiling point. In other words, the point of the kettle is to aggravate otherwise peaceful protesters. Of course, there are always some who are already non-peaceful (I don’t use the word violence because as far as I am concerned violence is against a person, damage to property is simply vandalism not violence;) however these make up a small minority. It has been shown that police kettles make a lot more people angry than those who were non-peaceful before the kettle began. Essentially, winding up a crowd of people in this way is simply incitement to riot, which is of course a crime.
Unfortunately, under PACE, ordinary citizens do not have the right to arrest a person pre-emptively (i.e. because they believe a crime is about to be committed). HOWEVER: there is a provision in the common law that allows any person to arrest another for a “breach of the peace”, and this provision includes pre-emptive arrest. The case in question – R v Howell  3 All ER 383 – states that a breach of the peace occurs “wherever harm is actually done or is likely to be done to a person or to his property in his presence to his property, or a person is in fear of being so harmed through an assault, an affray, A RIOT, unlawful assembly or other disturbance.” We have just established that a police kettle constitutes incitement to riot, so the logical conclusion is that any police officer who is a part of the kettle can be arrested by a member of the public at common law for a breach of the peace. And the best bit? If the officer in question tries to lash out with a baton or riot shield, well that’s resisting arrest, which is even more serious.
So, next time you’re stuck in a kettle, go up to the nearest officer, and arrest him (or her) at common law for a breach of the peace. Cite R v Howell if you need to. Get your friends and colleagues to do the same to other officers nearby. And together let’s prove that kettling is illegal!