Tens of thousands of anti-austerity protesters rallied on Sunday as British Prime Minister David Cameron's governing Conservative Party opened its annual conference.
A spokesman for the Trades Union Congress told AFP that 60,000 people were involved in the protest in the northwestern city of Manchester. Police have not given an estimate.
The TUC called the protest with the slogan "No to austerity, yes to workers' rights", citing what it called the government's "damaging programme of austerity and their attacks on the rights of working people and their unions".
The Conservative government is reducing spending in order to balance the books and ultimately get Britain to turn a profit so it can start to pay down its debts.
It is also pushing through legislation to curb strike action by ensuring a minimum 50 percent turnout in strike ballots.
The Conservatives won a majority of seats in the May general election.
Some demonstrators carried placards reading "Organise, Strike, Resist" and "Don't bomb Syria". Some wore pig masks.
James Penfold, 44, a nuclear waste scientist, said: "I think they're taking the cuts way too far. There are different ways of dealing with the deficit which involves taxation.
"What they are doing to the country is catastrophic and in many years we will really be regretting what's happened.
"I fear for our kids. There is so much debt and burden being laid upon them."
Pauline Gibson, 55, an unemployed nurse from Liverpool, wore a fake pig nose.
"I think the Tory cuts are very unfair and are damaging society," she said.
Steve Cannon, 52, a lecturer in film studies from Newcastle, said: "The cuts the Tories are bringing in are unnecessary, ideologically-driven and causing real pain up and down the country."
Linda Foley, 70, a retired nurse, from Manchester, held a "Defy Tory Rule" placard.
"I'm against Tory policies," she said.
"The changes they want to bring to the unions, I think that's just the beginning of what they want to do.
"I don't mind austerity as long as there's austerity for everybody and not just for the people of the orth and the working class."