After terrorist outrages like the one in Brussels, our leaders always say the same thing: ‘We must defend European values against these evil killers.’ It seems the Metropolitan Police didn’t get the memo. For they have just arrested someone — actually arrested someone — for tweeting something unpleasant about the Brussels attack, in the process trampling their coppers’ boots all over what is surely, or at least ought to be, the most important European value of all: freedom of speech.

The arrested man is one Matthew Doyle. He went viral after tweeting about a run-in he had on the day of the Brussels attacks: ‘I confronted a Muslim woman yesterday in Croydon. I asked her to explain Brussels. She said “Nothing to do with me”. A mealy mouthed reply.’

Now, if this encounter really did happen — and many have their doubts — it was a rude and ugly thing for him to have done. But to be arrested for tweeting about the incident, on suspicion of ‘inciting racial hatred’? To be locked up for hours, as Doyle has been, for saying something silly to a woman in the street and then tweeting about it? That is outrageous. The awfulness of his tweet pales into insignificance in comparison with the awfulness of his having been arrested for it. If you’re still shocked by his tweet rather than by the fact that 21st-century Britain arrests people for what they say, then your moral priorities need urgent rearranging.

This mad incident confirms how dangerous the Twittermob can be. Doyle’s tweet sped round the world. It was retweeted, tweeted about, covered in the press. Doyle was mocked and parodied, which is fine, but he was also branded dangerous and reported to the police, which is not fine. He fell victim to the Twittermob’s thirst for outrage, their never-ending search for someone or something they might feel thrillingly if temporarily disgusted by and virtuous in comparison to. This time some went even further, demanding that their sanctimonious fury be topped off with actual state action against the witch in their midst. ‘Arrest him!’, they hollered, and the police arrested him. For speaking. For saying what he thinks. For being an idiot. It’s a crime now to be an idiot? Arrest everyone.

The intensity of the Doylephobia — yeah, I’m using that word — is striking. It points to a desperation among certain observers to prove, against the evidence, that terrorist attacks are followed by outbursts of Islamophobia. In lieu of any serious backlash against Muslims following the Brussels attacks, with the people of Brussels instead remaining magnificently tolerant and peaceful, the Islamophobia industry must scour for any scrap of Muslim-hate it can find and then blow it up for the media and moralists to get whipped up about. So Tell Mama UK, which logs anti-Muslim incidents in Britain, has tweeted about the Doyle tweet more than 10 times. Hilarious. In the very act of constantly drawing attention to what one, sad man in Croydon said, Tell Mama unwittingly demonstrates that there isn’t much other Islamophobia to talk about. It undermines its own claims. Great work, guys!

The true horror here is not what Doyle said — it’s his arrest. That should make you angry. Because if we aren’t free to say silly things to people, and to tweet about it later, then we aren’t free. If we don’t have the freedom to say ‘Muslims should answer for the Brussels attacks’ — which I don’t think they should, by the way — then we don’t have freedom of speech. It’s that simple. Laugh at Doyle all you like, but his arrest is as much an attack on your freedom as it is on his freedom, because it tells us there are certain things we may not think or tweet without facing potential arrest.

‘The terrorists hate our freedoms’, people say. They aren’t the only ones. Angry tweeters, the easily offended, time-rich policemen… some people at the very heart of our societies seem to hate freedom too and want to rein in the right to speak freely. We have to defend our values against both nutters with bombs and a PC mob with Twitter accounts.