TENS of thousands of demonstrators have descended on the British capital in a noisy but peaceful protest at a government austerity drive aimed at slashing the country's debt.
Unions, anti-war campaigners, community groups and other activists poured down London's streets in a demonstration against reductions to public sector spending which officials are pushing through in order to rein in Britain's debt, which stands at more than STG1 trillion ($A1.56 trillion).
Although the austerity program has had some modest successes - the country's deficit has dropped slightly - the UK economy has shrunk for three consecutive quarters amid cuts at home and economic turmoil on the continent.
Brendan Barber, whose Trades Union Congress helped organise the march, said that the message of Saturday's protest was that "austerity is simply failing".
"The government is making life desperately hard for millions of people because of pay cuts for workers, while the rich are given tax cuts," he said.
Britain borrowed STG13 billion ($A20.25 billion) in September alone, and with other European countries - including next door neighbour Ireland - struggling to make good on their debt, and there is a general consensus that the UK budget needs to be rebalanced.
But the coalition government did little to endear itself with ordinary Britons when it reduced income taxes for the country's wealthiest citizens earlier this year.
And its leadership has struggled to fight perceptions of elitism which rankle many in this class-conscious country.
On Friday the Conservative Party's chief whip stepped down following a dispute over whether he'd described officers guarding the prime minister's official residence at Downing Street as "plebs" or warned them to "learn your (expletive) place".
News of Andrew Mitchell's resignation broke just as word was getting around that Chancellor of the Exchequer George Osborne had been spotted by a journalist sitting in a first class train carriage with a second class ticket.
Osborne paid for an upgrade, but story's humour was irresistible - newspapers lavished coverage on what many nicknamed "The Great Train Snobbery," and Osborne's misadventure was a talking point at the rally, which marched through the city beneath huge red and purple balloons emblazoned with union logos.
Some protesters shouted "no first class tickets here;" others booed as they passed Downing Street.
The marchers carried banners which read: "Cameron Has Butchered Britain", "24 Hour General Strike Now" and "No Cuts" as they marched through Whitehall towards Hyde Park.
They shouted "pay your taxes" as they passed a Starbucks coffee shop.
Police officers stood outside Starbucks, which has been involved in a row over its tax arrangements.
But unlike some rallies elsewhere in Europe which devolved into riots, Saturday's march appeared to go off without violence.
A police spokesman said there had been no arrests or incidents.
One group of children dressed up as government workers, including a nurse and a traffic warden.
Another child, dressed as a chef, held up a sign warning that Prime Minister David Cameron was "a recipe for disaster".
Ed Miliband, the leader of Britain's opposition Labour Party, was among the speakers to address the crowd in London's Hyde Park, following the march.
Miliband accused the prime minister of "clinging" to policies which were not working.
He said the coalition was cutting taxes for millionaires and raising them for everyone else.
"It is one rule for those at the top and one rule for everyone else."
Miliband was booed by a small section of a rally in Hyde Park when he said Labour would have to make "hard choices" if it was in government.
He pledged that if he became prime minister he would tax bankers' bonuses, support the building of 100,000 houses and end the privatisation of the NHS.
Similar protests were also held in Belfast, Northern Ireland's capital, and Glasgow, Scotland's biggest city.
