"This place says you're all free to use their toilets," the man with the loudspeaker shouts, coming out of a sandwich shop and addressing the crowds around St Paul's Cathedral. "Seriously, they don't mind if you're a customer or not. Do what you need to do in there. Have a shower. Do a poo."
The smattering of laughter has no impact on an organiser, who emerges from the crowd to urge him to leave the area. Anyone threatening the peace of the camp or its relationship with its neighbours shouldn't be there, he insists.
If that sounds oddly civilised for an anti-capitalist demo, then you should see the waste disposal centre, with separate bins for bottles, paper and rubbish. Or the kitchen, running entirely on donated supplies and volunteer cooks. Or the media centre, with running generators, work spaces and an embryonic video editing suite. The men and women in London's financial district aren't protesting. They're laying down roots.
"We've got church blessing," Giles tells me. He points to beautiful, morbid old St Paul's behind him, which offers us some respite from the wind. "In this building Rev Giles Fraser, who controls this square, has given us his blessing. This is a private square." He waves his hand across the scene, taking in a collection of around 40 tents and 200 activists all busily engaged in activities, from cooking to litter clearance to prolonged debates on the merits of the Tobin tax. "He's asked the police to go. If there are problems then we'll be thrown off. Our aim is to stay here peacefully. It might look like rag-tag operation but there's quite a lot of stuff going on here. We've got a ton of working groups gathered to get this message out clearly. We're encouraging people to come join us without being seen as a bunch of camping hippies."
Whichever way you look at it, it's impressive. I talk to Diaphel, who is running the media centre. Inside the tent, a handful of men are typing away on laptops while others charge their phones. All the wires lead to a generator outside with several cans of fuel beside it. They have another generator coming. He seems confident they can keep the power running indefinitely at the current rate of donation.
"We set up an inquiries email account," he says. "It's a place to upload all the photos and videos. We'll be exporting that to YouTube and a couple of other social media sites and from there we can provide it to press centres. We have a Twitter account. If anything is needed or large decisions are made they ask us to tweet it. We have donations of computers coming in, as well as external hard drives."
I can feel my professional qualifications fading to nothing. In 48 hours this guy has established an electricity centre, with charging docks for phones and laptops. He's providing photos and videos to mainstream journalists and issuing statements through Twitter, making it a fully-functioning PR department, complete with a small video editing suite and a work space.
"A lot of people are donating," he explains. "People walk by and ask what we need. One person is donating pizza on a regular basis from Enfield. One person in a suit and tie just got a job with a power company. He's getting us some solar panels. The guy that got us the petrol was from a local pub. An unemployed architect is advising us on organising the accommodation."
Next to the media hub, a collection of tents serves as a health centre. Inside, an activist is getting some rest with a couple of volunteer first aiders. Bridget, a respectable middle-aged woman who you'd trust with your house keys, is a registered nurse and a practising midwife. She's running things while the doctor, who just pulled a two-day shift, goes home and gets some rest.
"There were two potentially serious issues on the first night — an epileptic fit and a minor asthma attack," she says. "It's mostly minor issues — cut hands and the like. We were donated this extra tent yesterday so we have a treatment area and two bedrooms. We have another one as an overflow room. We have medical supplies. The doctor has looked over them, we liaised and he decided we need a little bit more equipment. He's happy with what we've got but he's going to order two rather large first aid kits and a couple of hundred space blankets. We have about 15 but we need a few more in case we get that cold snap."
As we talk, a middle-aged man with a copy of the Telegraph pulls a bemused look as he surveys the scene. I ask him what he makes of it. "I'm surprised it hasn't happened before," he says instantly. "Been rather slow to come about."
Dani agrees. A student from Pittsburgh, she patiently answers my questions while decorating a large white sign with slogans. "I was really impressed with how it spread out from Wall Street," she says. "It's in LA, Washington DC, Seattle, Pittsburgh, Philadelphia, Minneapolis. I go to Dartmouth college. They're occupying there. It's the start of something really wonderful."
She's right. Across the US, Europe and Australia similar camps are being set up, with a strangely neutral response from the press and the cautious sympathy of passers-by. Of course, something this diverse has no concrete aims. It is not in a position to write out a manifesto yet, beyond an opposition to bank bailouts and public sector spending cuts. But this is how popular movements begin, with generalised discontent. Sometimes they fizzle out. Sometimes they build to something bigger, especially when their anger is focused and resonates with the public. In London, the process requires protesters to maintain the camps as a focal point for the movement, as Zuccotti Park is for Occupy Wall Street. At the current rate of organisation, that seems entirely credible.
For now, no-one wants to talk about the long game. It's impressive enough that they're all here, in the heart of the City, establishing something which expresses their anger and frustration. Their only concern is today.
I ask Dani what comes next. "Well, I want this sign to be finished," she replies, as if I'm over-complicating things. "I've been working on it for two hours."