Don't people have the right to protest against the invasion of Iraq?

I've been shocked by the prosecution of a handful of Muslims who protested against the actions of the British Army in Iraq. I'm not concerned with whether they are right or wrong in what they said. They shouted some silly slogans, and the rumour is they thought the Army regiment in question had some Christian religious significance: they thought the Anglian regiment was the "Anglican regiment." That's not the point. My point is that we tell ourselves, and them, how superior our way of life is to the way of life in the countries to which they owe their allegiance. Then when they take advantage of British freedom of speech and freedom to protest, they find themselves arrested and convicted of a criminal offence. This isn't how a liberal democracy conducts itself. Is it?