Hundreds of demonstrators besieged the hotel where David Cameron gave a speech to the Conservative Party's Spring Conference on Saturday.
In a bid to pressure the Prime Minister to either resign or close tax loopholes, protestors marched from Downing Street to the entrance of The Grand Connaught Rooms in London.
Many of those attending the rally told The Huffington Post UK they believed the "tide had turned" on Cameron since the Panama Papers revealed his late father's tax arrangements.
Jack, a second-year junior doctor wearing his bright blue scrubs to the demo, told HuffPost UK: "I've not found the [Panama] revelations at all that surprising.
"We've known for six years we have a Cabinet full of millionaires, and that's what millionaires do: avoid tax.
"This is very damaging for Cameron and we should put the pressure on and show him it's completely wrong to vilify people on benefits when he's deny taxes that are due."
Beata, a Polish citizen whose lived in the UK for 11 years, said: "We know it's all fucked up but the hypocrisy that was highlighted by the Panama Papers which shows Cameron benefiting until he became Prime Minister... he's daring to say we should pay the taxes?
"I think at the moment, he is at his weakest."
Despite having been organised on Friday morning, around 1,000 demonstrators attended Saturday's march.
Abi Wilkinson, one of the event’s organisers, said on Friday: "We’re hoping to have a fun, tropical party vibe and to get ordinary people out rather than committed activist types."
The atmosphere was jovial, with tropical music blaring from portable speakers at both Downing Street and the Connaught conference venue.
The spectre of a pig piñata, waving high above the march, guided protestors towards the Tory Spring forum, being held a mile away from Number 10.
The piñata was ceremoniously whacked by demonstrators in front of the conference venue.
Its creator told HuffPost UK he decided to get involved in Saturday's action, and thought the image of a pig was the natural choice.
Artist Gavin Turk said: "The idea of hanging him up and everyone hitting him with the stick appealed to me.
"I wasn't really sure what to expect, so far it all seems very jolly and everyone is really together in saying we think it's rubbish what the government are up to.
"It seems strange that if [David Cameron] knows and has knowledge of tax avoidance situations then he should get right on to it to benefit everybody and to benefit society.
"He's turning the country into a 'moneytocracy' - if you have the money you can do what you like.
"Greed is guiding this, it's limiting people's choice and it's making society unwell."
Kathleen, who has been involved in protests against cuts in the past, told HuffPost UK: "I'd been quite clued into tax avoidance since the Private Eye investigation into Vodafone.
"But I'm so happy the Panama Papers have come out as it gives us a lot of evidence, very specific evidence.
"We can literally point at specific people - it couldn't be better. It's easier for people to unite around this when they have specific detail.
"I think this is going mainstream. There's so much we don't know about yet."
Esme, wearing a bright red Momentum badge, said: "It's important to do this today to keep the issue going.
"I don't think Cameron will go today but the idea is to put as much pressure on and to let him know the mood has changed and he's not welcome.
"Even if it's within the Tory party itself, they're weak enough as it is."
The protest came as David Cameron used his speech at the Spring Conference to say there is only one person to "blame" for the furore over his taxes.
With HuffPost UK photography by Ryan Barrell