I was travelling on a bus going north from Waterloo Station. The route went past the grotesque KFC-branded IMAX cinema, and then the National Theatre as it crossed the river. As we approached Trafalgar Square, I spotted out the window a young man of about college age.

He was crossing a typically busy road near all the garish tourist traps. He was with a group, clearly his friends. He was holding a large angry red sign under both arms, which had something printed on it in large black capital letters. He wasn’t holding it up for everyone to see, he seemed to be merely carrying it somewhere.

I tried to make out what it said, but my view was obstructed by street signs and pedestrians and the other passengers. On top of that, the way he was holding it ended up displaying the message on its side. He and his friends disappeared into the rest of the crowd, and Initially I thought nothing more of it.

Later, as I walked near Shaftesbury Avenue, I was surprised when I noticed a stranger walking towards me. It was a girl about the same age as the young guy I had seen; she was on her own. She was holding an identical sign.

It was clearly the same size, same square shape, same colours, same font – possibly Gill Sans, in an apparent ironic mimicking of that wretched false meme, “Keep Calm And Carry On”. She was even holding it in the same way that the boy had been doing – carrying it like the huge folders I remember art students lugging around between classes.

Again, the text was presented on its side. Despite that, I was now able to read it. The message was:

STOP READING THIS SIGN

KEEP RUNNING