Dismaland is not all crap jokey installations, however. There are political one-liners here as well as artistic ones. People are queuing up to go inside a caravan with intense displays about the evil of our fascist police state. There is also a huge model of said fascist police state, with tiny police cars everywhere, blue lights flashing right across a diorama of a city at night.

The irony of the security on the way into Dismaland is underlined by all the references to CCTV and the wicked security establishment that pervade it. Yet that obvious double standard goes much deeper. Dismaland is a kind of consummation, for me, of all that is false about Banksy. It claims to be “making you think” and above all to be defying the consumer society, the leisure society, the commodification of the spectacle. Disneyland packages dreams, Dismaland is a blast of reality. But it is just a media phenomenon, something that looks much better in photos than it feels to be here. “Being here” is itself just a way of touching the magic of Banksy’s celebrity – that’s why everyone is taking pictures. This is somewhere to come to say you went. As an actual experience it is thin and threadbare, and I found, to be honest, quite boring.

I felt I was participating in a charade where everyone has to pretend this is a better joke than it is. In reality the crazy fairgrounds and dance tents at rock festivals are far more subversive – because they are joyous.

Perhaps you need intoxicants to enjoy Dismaland, and I was there at 11 in the morning. But its failure to create joy is self-defeating. Funfairs really are strange, wild places, as film-makers have known since Tod Browning made Freaks and rock music has known since the Doors recorded Strange Days. But in Dismaland, the rather well established idea that fairs are bizarre is not taken anywhere new or interesting.

As a news story, a media sensation, it works wonderfully – but up close, this is a Potemkin theme park. It’s not an experience, just a pasteboard substitute for one. Indeed, it is a mere art exhibition. Dismaland does not offer the energy and danger that real theme parks do. Instead, it brings together a lot of bad art by the seaside.