Oh, we believe in property rights of a sudden, do we?

I very much doubt The Misfortuneteller was the first person to come up with this gag. I expect joke memorials have been around for as long as adulterers or any other kind of joke have. Seems a bit presumptuous to believe you're the first person in history to come up with a particular gag.

well, people are free to sign their work. Those creating a brand or a business do. FWIW these “everyone is talking about…” story was laughable anyway. Maybe they did it in Clifton Village – but as Clifton Village can’t even cope with the bike parking, they are not representative of the city. The main topic in the street art community seems to be: finally it has stopped raining! Lots of new work going up
#streetart

I don't really see how a plaque on a bench, in isolation it seems to be in, makes any difference to the original creator in terms of benefit. I mean, I'm not against crediting the author, but another line like "credit goes to..." on the plaque would kinda ruin the joke.

In the end, jokes are inherently forgetful of their authors.