London's financial district has begun its working week with a new, vocal and, protesters hope, permanent voice of dissent at its centre in the form of a tent encampment objecting to the excesses of the global financial system.

Around 150 tents, plus various makeshift tarpaulin shelters, remained clustered around the west side of St Paul's Cathedral in the City almost 48 hours after activists from the Occupy the London Stock Exchange group first set up camp.

The unofficial alliance, organised through Facebook and Twitter groups and modelled on similar protests on Wall Street and elsewhere, had hoped to base itself inside Paternoster Square, a business development adjoining the cathedral, which houses the Stock Exchange headquarters, as well as the London base of Goldman Sachs.

However, police on Saturday prevented an initial group of several thousand protesters from entering the square. Their presence on a small piece of open, paved ground by St Paul's was boosted over the weekend when the cathedral's canon chancellor, the Rev Dr Giles Fraser, said he supported the right of the "good natured" crowd to remain.

While the site is slightly away from the traditional heart of the banking and investment district, it is sufficiently central for a number of largely good-tempered debates to break out on Monday morning as suited workers were greeted by slogan-chanting protesters as they walked to their offices.

"We had quite a long chat with one man just now," said Mark Weaver, 30, who travelled from Leeds to join the camp on Saturday. "His view was that we should wait three years and vote in a general election if we wanted to make a difference. He said: 'What if I turn up here with 10 times as many people who have jobs and don't object to the financial system – will you give up and leave?'"

"It was very polite but it's fair to say we didn't agree on much," added Nick Stibbs, 35, from Cambridge.

Looking to the example of New York, the protesters have taken great efforts to ensure the camp does not produce any litter or other mess. While protesters await the arrival of makeshift toilet blocks, they have been under strict instructions to only use nearby public conveniences.

The police have, in general, been similarly helpful, said Greg Williamson from Swansea – at 74, one of the older participants. Police plans on Sunday night to fence the camp off with metal railings were abandoned, he said, after campers offered to instead chalk out a line beyond which tents should not be pitched to ensure walkways were not blocked, a plan that seemed to be working.

"It's a lovely atmosphere," said Williamson, whose London-based brother had just delivered him a flask of tea and an apple for breakfast. "You don't get much sleep, though, with the clock chiming every quarter of an hour."

The intention, if police do not clear the camp, is to keep it in place indefinitely, with a rolling presence of different activists. Some, like Williamson, say they plan to remain as long as they can.

While appearing somewhat haphazard, the encampment has organised itself in a series of ways, with one tarpaulin shelter producing communal meals, another accepting donations of food and camping equipment, while another area organised rotas and the mass meetings at which decisions are made.

The interactions between activists and Monday-morning commuters were generally friendly, if mocking on the part of the campers. "Shares only, please," read the cardboard sign next to a protester serenading office workers on a set of bagpipes.

"I was just offered a hug," said one immaculately suited male investment banker, who asked not to be named. "I thought about it, but he was a man and he'd spent a couple of nights in a tent, and I've just had a shower, so I decided maybe not."

The banker said that while he doubted the efficacy of the protest, he could understand its aims.

"I admire their spirit. I never dreamed of becoming a banker, but I ended up with a mortgage and children and it's a good job. But if I was younger I'd probably be joining them."