Teachers and civil servants marched through the streets and picketed government buildings across Britain today in protest at planned pension reforms.
The strikes, echoing protests across continental Europe against austerity imposed to reduce debt, are the first in what unions say will be a wave of action against steps by the government that will cut the value of public sector pensions.
The march, which stopped traffic on some of London's main thoroughfares, involved thousands of workers and supporters carrying banners and blowing whistles.
Today's protests involved about one in eight public sector workers, but other unions are gearing up for stoppages later this year if talks break down.
Nearly half of schools were expected to be closed today and another 40 per cent were expected to partially shut, a teaching union estimated.
However, a government spokesman said early indications were that turnout was "perhaps less than the unions had claimed." Exact numbers were not expected until later in the day.
Air passengers faced some delays as immigration officials joined a walkout that could involve up to 750,000 workers.
Aer Lingus and Ryanair reported no disruption to their planned flight schedules today as a result of the UK strike. There were some delays on international flights arriving at Belfast International Airport. However, a spokeswoman said UK flights and all other departures were not affected.
Courts and government buildings in Britain were also affected by the strike action. The Metropolitan Police said 90 per cent of staff dealing with calls from the public did not turn up for work.
Dozens of marches and rallies were arranged across the country, and were generally peaceful. "This country is being led by people who are privileged, people who earn too much money... The gap between rich and poor is getting bigger. We don't think it should be us who are made to suffer for it," said Martin Pitcher (35), a primary school teacher taking part in the biggest march in central London.
"We are here to protect our own pensions. We are also fighting for pensions and against overall government cuts generally. I'm worried about my own retirement because when I add up what I'm going to get, it's just not liveable," said Simon Korner, a 54-year-old lecturer.
"It's about standing up to the bully," said sports teacher Martin Patching at a rally in Welwyn Garden City, Hertfordshire. "I hate striking but it gets to the point where you've got to stand up with your colleagues and say enough's enough."
Prime Minister David Cameron has condemned the strikes as irresponsible, saying that talks between unions and ministers have not concluded.
Mr Cameron argues that longer life expectancy means public sector pensions must change to ensure that they are affordable. The changes are part of government plans by 2015 to virtually wipe out a budget deficit that peaked at more than 10 per cent.
Consequently, workers face higher contributions to their pensions and longer working lives. The proposals have hit a raw nerve at a time of wage freezes and job insecurity.
Union leaders assert that their members are bearing the brunt of a financial crisis caused by rich bankers.
Analysts said the protests would challenge the government anew after it retreated on plans to restructure state-funded health care following lobbying from the medical profession.
Markets, which have reacted positively to government deficit-cutting plans, would take fright at any sign of a government climbdown over an issue like pensions.
Some Britons sympathise with the strikers but others say they are being unrealistic at a time when households have suffered their biggest fall in disposable income for more than 30 years.
"The state of the country is pretty bad. They are a bit too focussed on themselves," said Michael Hayes, a railway manager from the London suburb of Chingford.