Teachers, nurses and border guards walked out on Wednesday as up to two million state workers staged Britain's first mass strike for more than 30 years in a growing confrontation with a deficit-cutting coalition government.
Public sector employees are protesting over reforms that unions say will force them to work for longer before they can retire, and pay more for pensions which will be worth less.
Their anger has been fuelled by new curbs on their pay and additional job cuts outlined on Tuesday when the Conservative-led government cut economic growth forecasts and said its tough austerity programme would last until 2017.
Why are the government picking on us in the public sector?, said Kevin Smith, 54, picketing in pale winter sunshine outside parliament in London, where he works as a security officer.
We are going to get a 1 percent pay rise for the next three years. We had no rise the last two years, before that we were getting lower than inflation rises. So how long is it going to last?
Chancellor George Osborne condemned the strike that has closed most schools in England and Wales and forced hospital to cancel all but the most urgent operations.
The strike is not going to achieve anything. It's not going to change anything, Osborne told BBC TV. It is only going to make our economy weaker and potentially cost jobs.
The government, trying to turn around a debt-laden economy teetering on recession, says reform is needed as people are living longer and public service pensions are unaffordable.
The strikes mirror protests in continental European countries where governments are trying to juggle budget deficits with the needs of an ageing population.
HEATHROW DELAYS AVOIDED
Airlines said they were cutting flights into Heathrow, Europe's busiest airport, because of fears of long delays and overcrowding due to the passport control strike.
The government has flown some embassy staff home and recruited volunteers from other departments to help take the place of striking border guards and delays that had been feared had not materialised on Wednesday morning.
Due to the effective contingency plans we have put in place with the airlines and the UK Border Agency over recent days, immigration queues are currently at normal levels, airport operator BAA said.
Passengers arriving later in the day could face delays, it added.
At Heathrow, a marquee, rows of chairs and toilets had been set up outside in preparation for overcrowding.
Brendan Barber, general secretary of the Trades Union Congress, an umbrella group coordinating the strike, said workers were no longer being asked to make a temporary sacrifice, but accept a permanent deep cut in living standards.
Our economy can afford decent pensions, the cost of public sector pensions is due to fall over coming decades, Barber told Sky News. We're not going to solve our problems in our economy by hammering down the living standards of six million public service workers.
A coalition of 30 trade unions are taking part in the strike, billed as the biggest walkout since action during the Winter of Discontent in 1979 that helped Conservative leader Margaret Thatcher sweep to power.
We are striking because the government is cutting the pensions, they are telling us to work more hours and they are cutting jobs at our schools, said Hasina Carroll, a UNISON union member and support worker at St. Matthew Academy school in the London suburb of Blackheath.
(Additional reporting by Michael Holden and Keith Weir; editing by Diana Abdallah)