Climate change protesters occupied part of London's Smithfield Market, calling for the UK to transition to a vegan diet.
One man was arrested as up to 400 protesters from Animal Rebellion, an off-shoot of Extinction Rebellion, set up camp in the centre of the 800-year-old Farringdon meat market.
There were also stalls filled with "food that will make up our future food system" during the 18-hour protest, which began on Monday night.
"If the government were to take the climate change seriously, one of the biggest things they can do is look at the food systems," said Alex Lockwood, a spokesman for Animal Rebellion.
Agriculture is currently responsible for about 9% of the UK's greenhouse gas emissions, mostly from methane.
The group claims animal farming uses 70% of agricultural land, and is the leading cause of deforestation, biodiversity loss, and water pollution.
Mr Lockwood said: "The meat industry is on its knees, but there are still no subsidies to help farmers who want to transition to a plant-based food system.
"We're not at Smithfield to disrupt ordinary people from their work.
"We're here to send a message to the Government: this industry at the heart of the climate emergency has to be helped transition to a plant-based food system, with just processes in place to ensure workers can still feed their families, while properly tackling the climate catastrophe."
A Citizen's Assembly, with speakers including TV presenter Chris Packham, was held as activist camped out overnight on Monday.
Protesters also held a candlelit vigil "in memory of all the animals who lost their lives".
The activists left the market by noon on Tuesday.
The group is demanding "an end to the industries of animal agriculture and fishing" and to transition the UK to "a sustainable and just plant-based food system by 2025".
A Government spokesperson said: "The UK is already taking world-leading action to combat climate change as the first major economy to legislate to end our contribution to global warming entirely by 2050.
"While we share people's concerns about global warming, and respect the right to peaceful protest, it should not disrupt people's day-to-day lives."
Smithfield Market is the largest wholesale meat market in the UK, and is usually open from 02:00 until 08:00, supplying restaurants and butchers across London.
The protest was organised with the consent of the City of London Corporation, which owns the Smithfield Market building.
Activists were allowed to occupy the central passage of the market, blocking two main entrances into the market, but leaving loading bays free.
Traders were also warned of the protest and plans were put in place to minimise any loss of sales.
James Tumbridge, chairman of the corporation's markets committee, said: "We have worked positively with Animal Rebellion and other stakeholders to facilitate a peaceful demonstration that does not prevent the safe operation of Smithfield Market.
"The City of London Corporation is already taking bold and radical steps to ensure that the Square Mile is leading the way when it comes to reducing emissions, improving air quality and tackling climate change."
One protester, a retired lorry driver who gave his name as Brian, said: "People tell me to get a life, but I've got a really really good life.
"I never imagined I'd be doing this but it was a matter of conscience.
"If all these things are happening, when my time comes I don't want to think I didn't do anything to stop it."
Dave Boddy, who has worked in Smithfield for 58 years, said he would like to see the protest "banned".
"It has disrupt the whole meat trade, it's going to disrupt everywhere. Let's hope it doesn't carry on too long
Mr Boddy, who started meat trading at 16, said: "It won't get them anywhere. Around 90% of the people in this country eat meat and I can't see them all going vegetarian."
Nehal Patel said the protest "had made getting home extremely hard which was frustrating as I'm pregnant".
"The protest is affecting the wrong people," the Merrill Lynch audit manager added.
Sebastian Constantine, a banking analyst who commutes through the market, said he "fully supports" the protest.
"As a vegan I hate walking through the market each morning, with the smell of meat and blood on the floor.
"The market is outdated and deserves to end."