I saw someone being arrested last night. I don’t know why that surprised me so much: I’ve lived on the outskirts of Brixton for over a year for god’s sake, it’s a miracle I haven’t witnessed crackdown at dawn.

I was toddling along Victoria wondering why I wasn’t a hell of a lot drunker than I rightly should have been after so much vodka, when I walked through the barriers and smack into the middle of this tall guy in a lumberjack shirt arguing with some yellow fluoro-policemen.

I had no idea what was going on, but they’d obviously being at it for a while. It was heated. They told him to calm down – he didn’t, for whatever reason. They then leapt on him, got his head right down and forced him to the floor. “STICK OUT YOUR ARM!” one of them bellowed. I couldn’t even see if his arm was out or not because he was covered in yellow, but he wasn’t shouting anymore.

A girl clutching a guitar case was crying something unintelligible at the pile of bodies. A female police officer took her to one side and looked like she was explaining, matter of factly. Maybe not a girlfriend then. When something bad happens in London, you usually get a crowd of gawkers, making sure it’s not them. This time people stood there in silence, like a Greek Chorus. A muffled voice from the pile announced he was arresting the man and there was a glint of handcuffs.

One of the policemen stood up and took off his helmet. He was just a baby, only 18 or 19, grinning shyly at nothing in particular. You could tell he was buzzing, thinking: “OK, that was pretty fucking cool!” like I did after I went to my first press conference.

(Everyone downs on policemen. Within my fluffy, safe middle-class world that’s mostly because we have Guardian ideas of liberalism, or we do illegal things and they spoil our fun. But they got the bastards who mugged my housemate, so there.)

Another policewoman turned round. “Right, you can all go downstairs now,” she said briskly. We did, like a factory line: Chorus exits straight down the escalators and job done.

I sat down and started scribbling down what had happened so I could think about it later. The guy next to me must have been reading it. “Did you see that?” he asked. He’d gone down the escalator just as I’d come in. He was deaf, fiercely expressive and with good speech and together we pieced together what must have happened.

”Do you think the police were right?” he asked, over and over. “God knows,” I said, “I didn’t see what happened before. They must have had reason” “He looked drunk,” he said, miming a glass and making ‘good grief’ eyebrows. “The girl bumped into him with her guitar case and he kicked off.” I think this is what he said. I had to ask him to repeat himself and felt like I did when I went to Germany aged 12 and had to go shopping: really thick.

”Have you always been deaf?”

“Yeah, since birth. I learned to speak by reading lips. That’s how I hear.” Laughs. “You’re difficult to understand.” Fair point: when I’m excited I speak like a typewriter.

I spoke more with my hands and eyes, less and more clearly with my mouth. “I don’t know much,” I said, trying to excuse my puny language against his. ”ABC on the fingers. My name is Kat.” Fingers in towards the chest, push out from lips, then your own movement for your name.

An enterprising school teacher of mine called Miss Simms – sarcastic to the point of godliness – decided that instead of dossing around in the half-hour we had to take the register in the mornings, we’d learn sign language. We did it for a year –alphabet, basic phrases, names – and then swapped form tutors so we never did it again.

I’d always kind of regretted it, if only because I knew there’d be one day when I’d meet someone who was deaf and it would be nice to communicate with them in their own language rather than lip reading. Hey, I did.

Earlier that evening, The Journalist and I were talking about communication and language.

”I want to be fluent in Japanese and Welsh by the time I die,” he said. It might have been German, I can’t remember.

”I really hate the fact I’m losing my languages,” I said, doing absolutely nothing about it.

I screwed up my first two years at university. It was only when I got away from there, to France, to Italy, that it finally clicked why I was still studying and it wasn’t so I could discuss La Princesse de Clèves. It’s so that you can talk about comics with people you meet at house parties, or piss around telling stupid jokes. It’s getting a proper insight into a different culture and realising that everyone has something in common, even when they think they’re entirely different. Even if it’s something as mundane as queuing up to buy stamps.

Language is brilliant. Music is language. Communication is everything.

“We’re so useless at communication,” said The Journalist, rolling his eyes as if to encompass the entire UK.

We are. But at least we’re trying to be useless in languages other than our own, to speak to people outside out own, little worlds.